IN F O R M A T IO N T O U S E R S T he m o s t a d va n ce d te c h n o lo g y has been use d to p h o to ­ g ra p h a n d re p ro d u ce th is m a n u s c rip t fro m th e m ic ro film m aste r. U M I f ilm s th e t e x t d ir e c t ly fr o m th e o r ig in a l o r copy s u b m itte d . T h u s , some th e s is a n d d is s e rta tio n copies are in ty p e w r ite r face, w h ile o th e rs m a y be fro m a n y ty p e o f c o m p u te r p rin te r. T he q u a lit y o f t h is r e p ro d u c tio n is d e p e n d e n t u p o n th e q u a lity o f th e copy s u b m itte d . B ro k e n o r in d is tin c t p r in t , c o lo re d o r p o o r q u a lit y illu s t r a t io n s a n d p h o to g ra p h s , p r in t b le e d th ro u g h , s u b s ta n d a rd m a rg in s , a n d im p ro p e r a lig n m e n t can a d v e rs e ly a ffe c t re p ro d u c tio n . I n th e u n lik e ly e ve n t th a t th e a u th o r d id n o t send U M I a com plete m a n u s c rip t a n d th e re are m is s in g pages, these w i l l be n o te d . A ls o , i f u n a u th o riz e d c o p y r ig h t m a t e r ia l had to be rem oved, a n o te w i l l in d ic a te th e d e le tio n . O versize m a te ria ls (e.g., m aps, d ra w in g s , c h a rts ) a re re ­ p ro d u ce d b y s e c tio n in g th e o r ig in a l, b e g in n in g a t th e u p p e r le ft-h a n d c o rn e r a n d c o n tin u in g fro m le f t to r ig h t in eq ua l sections w it h s m a ll overlaps. E a ch o r ig in a l is also p h o to g ra p h e d in one exposure a n d is in c lu d e d in reduced fo rm a t th e ba ck o f th e book. These a re also a v a ila b le as one exposure on a s ta n d a rd 3 5 m m s lid e o r as a 17" x 23" b la c k a n d w h it e p h o to g r a p h ic p r i n t f o r a n a d d it io n a l charge. P h o to g ra p h s in c lu d e d in th e o r ig in a l m a n u s c r ip t have been re p ro d u c e d x e r o g r a p h ic a lly in t h is copy. H ig h e r q u a lit y 6" x 9" b la c k a n d w h it e p h o to g ra p h ic p r in t s a re a va ila b le fo r a n y p h o to g ra p h s o r illu s tr a tio n s a p p e a rin g in th is copy fo r a n a d d itio n a l charge. C o n ta c t U M I d ir e c tly to order. University Microfilms International A Bell & Howell Information C om pany 300 North Zeeb Road, Ann Arbcr, Ml 48106-1346 USA 313/761-4700 800/521-0600 O rder N um ber 9012086 Origin and geochem ical evolution o f th e M ichigan basin brine Wilson, Timothy Peter, Ph.D. Michigan State University, 1989 C o p y rig h t © 1 9 8 9 b y W ils o n , T im o th y P e te r. A ll rig h ts reserved. UMI 300 N. Zeeb Rd. Ann Arbor, MI 48106 ORIGIN AND GEOCHEMICAL EVOLUTION OF THE MICHIGAN BASIN BRINE By Timothy Peter Wilson A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Geological Sciences 1989 ABSTRACT ORIGIN AND GEOCHEMICAL EVOLUTION OF THE MICHIGAN BASIN BRINE By Timothy Peter Wilson Chemical and isotopic data were collected on 126 oil­ field brine samples and were used to investigate the origin and geochemical evolution of water in 8 geologic formations in the Michigan basin. The data were analyzed using graphical, thermodynamic modeling, and statistical methods. Cl/Br ratios suggest that the Michigan basin brines originated from evapo-concentrated seawater. Two groups of brine brine are found in the basin, the Na-Ca-Cl in the upper Devonian formations, and Ca-Na-Cl brine from the lower Devonian and Silurian aged formations. Devonian Berea, from seawater brine evolved Traverse, concentrated by aluminosilicate bacterial and Dundee into halite or by formations halite precipitation, reactions, action the Water in the upper and CaS04 the originated facies. This dolomitization, removal of precipitation. S04 The by stable isotopic composition (D, 0) is thought to represent dilution of evapo-concentrated seawater by meteoric water. brine origins sabkhas and are: lagoons, (1) seawater reflux down evaporation into the Possible in coastal sediments, and Timothy P. Wilson later dilution by meteoric water, or (2) residual fluids squeezed from the underlying Devonian and/or Silurian salts during compaction mixed with dilute water in the overlying formations but maintaining saturation with halite. Water in the lower Devonian Richfield, Detroit River Group, and Niagara-Salina formations is very saline Ca-Na-Cl brine. Cl/Br concentrated suggest through the it originated halite and into from the seawater MgS04 salt facies, with an origin linked to the Silurian and Devonian salt deposits. increased the Dolomitization Ca/Na, and aluminosilicate halite precipitation reactions removed K, and bacterial action or CaS04 precipitation removed S04 from this brine. Additional CaCl2 enrichment may have occurred from the diagenesis of the Salina A-l potash salt. isotopes reflect the seawater origin, but may Stable have been affected by carbonate equilibria at higher temperatures. Water chemistry in the Ordovician Trenton-Black River formations indicates dilution of evapo-concentrated seawater by fresh or seawater. Ordovician seawater, Possible present-day saline end-members upper Devonian Ca-Cl brine from the deeper areas in the basin. include brine, or Copyright by TIMOTHY PETER WILSON 1989 ACKNOWLEDGMENTS I would like to acknowledge the help given by the following companies and individuals: The Michigan oil and gas industry, especially the Dart Oil and Gas Company, Shell Oil, Amoco Oil Company, Mossbacher Production Company, Wiser Oil, Miller Oil, and Wenner Production Company. The faculty and staff at the Department of Geological Sciences, Michigan State University. Argonne National Laboratory. Dr. Alden Carpenter, Chevron Research Co. I would also like to acknowledge the following agencies that funded this project: The American Chemical Society Petroleum Research Fund. Geological Society of America. American Association of Petroleum Geologists. Amoco Production Company. Shell Western Exploration and Production Company. Department of Energy Educational Programs, Argonne National Labortories. Department of Geological Sciences, Michigan State University. I would like to express my sincere thanks to the teachers and friends that have helped me in this work: Dr. David Long, Dr. Grahame Larson, Dr. Duncan Sibley, Dr. William Cambray, Dr. John Wilband, Dr. William Cooper, Dr. Richard Cooper, Dr. Richard Heimlich, Mike Takacs, Dale Rezabek, Jim Tolbert, Joe McKee, and Dr. Douglas Lee. Finally, I would like to express my heartfelt gratitude to my wife Janet, and to Dave. Without your support, friendship, and understanding, this work would not have been possible. TABLE OF CONTENTS Chapter 1: Geochemistry of water in Devonian aged formations, Michigan Basin Introduction ............................................ 1 This S t u d y .............................................. 3 Study A r e a ......................................... 4 Analytic M e t h o d s ........................................ 15 Geochemical R e s u l t s ..................................... 19 Distribution of brine chemistry .................. 21 Major ion c o m p o s i t i o n ............................ 25 Geochemical o r i g i n .......................... . . .36 Geochemical evolution ............................ 37 Water-rock i n t e r a t i o n s ....................... 4 0 D o l o m i t i z a t i o n ................................40 Alumino-silicate reactions , . ..49 Other s a l t s ...................... . ........... 51 Model for brine evolution based on geochemical d a t a ........................ 53 Stable isotope results ................................. 54 Interpretation ...............................57 D i s c u s s i o n ......................................... 60 Saline endmember ............................ 61 Apparent modern-day meteoric water ......... 62 Linking the isotopic and chemical data . . . 64 Model for brine evolution based on isotopic d a t a ............................ 71 Summary ....................................... 75 Chapter 2: Origin and evolution of water in the NiagaraSalina and Ordovician aged formations, Michigan Basin Introduction ............................................ 78 Study Area, Niagara/Salina reefs ...................... 82 Reef h i s t o r y ...................................... 83 Salina s a l t s ....................................... 87 Ordovician formations ............................ 89 M e t h o d s .................................................. 92 General r e s u l t s ..........................................94 Niagara/Salina formation r e s u l t s ................. 97 Ordovican formation results ...................... 101 Isotopic r e s u l t s ................................... 105 TABLE OP CONTENTS (cont'd.). Geochemical evolution of Niagara/Salina b r i n e ............................... 105 C a - M g - S r ....................................... 107 P o t a s s i u m ...................................... Ill Mass balance model ............................... 113 Enrichment in CaCl2 . . . . = > ..................... 119 Isotopic evolution . . ............................. 127 Model for the origin and evolution of Niagara/Salina formation w a t e r s ................ 134 Origin of Trenton-Black River formation brine ........................................ 137 St. Peter Sandstone w a t e r ........... 143 Isotopic evolution ..................................... 14 5 148 C o n c l u s i o n s ........................ Estimation of Br in s a l t .......................... 151 Appendix A. Statistical evaluation of Michigan Basin brines 152 This s t u d y .......................... 153 Univariate s t a t i s t i c s ....................................154 Data distribution . . . . . . .................... 154 Average brine composition ......... . 158 Comparision with seawater ........................ 163 Formation comparision ............................. 166 Correlation c o e f f i c i e n t s ........................... 169 Multivariate s t a t i s t i c s ..................................172 Interpreting f a c t o r s ............................... 174 Past work .......................... . . . . . 1 7 4 Factor patterns ...................................181 Q-mode methods and r e s u l t s ......................... 185 R-mode factor methods ............................. 186 R-mode results ........................... 187 Effect of pH v a r i a b l e .............................. 211 Effect of partialling out s a l i n i t y ................. 211 Effect of rotation method ....................... 212 Interpretation of R-mode r e s u l t s .................. 213. D i s c u s s i o n ............. 216 C o n c l u s i o n s ...............................................217 Appendix B. M e t h o d s ........................................... 219 Brine s a m p l i n g ....................................... . . 2 1 9 Field a n a l y s i s ............. 220 D i s c u s s i o n ............. 221 Analytic m e t h o d s ................... . . 223 Sample preparation ........................... 225 Ca, Mg, S r ........... 227 Na, and K ......................................... 227 Rb, Cs, L i .......................................... 227 vi i TABLE OF CONTENTS (cont'd.). S i l i c a .............................................. 228 B o r o n .............................................. 229 NH4N ................................................ 229 C h l o r i d e ............................................ 230 B r o m i d e ............................................ 230 I o d i n e .............................................. 231 S u l f a t e ............................................ 232 TDS and d e n s i t y ................................... 232 Oxygen and hydrogen i s o t o p e s ...................... 233 Strontium i s o t o p e s ................................. 235 Subsurface temperature and pressure ............. 2 36 Analytic Error-charge b a l a n c e .......................... 239 Error e s t i m a t e ..................................... 240 Appendix C. Analytic d a t a ............................... 248 Bibliography ............................................ viii 2 58 LIST OF TABLES Table 1-1. Chapter 1 Estimated formation volumes in the Michigan basin................. 8 Table 1-2. Summary of Devonian formation geology, Michigan basin................................. 11 Table 1-3. Components measured and analytic methods. . .18 Table 1-4. Average composition of formation waters. Table 1-5. Apparent meteoric water compositions . . . . Table 1-6. Results of mixing example..................... 66 . .20 56 Chapter 2 Table 2-1. Average composition of Niagara/Salina and Ordovician Formation waters, Michigan basin. 95 Table 2-2. Evolution of Niagara/Salina brine ......... 115 Table 2-3. Bromide concentrations characteristic of potash m i n e r a l s .......................... 12 3 Table 2-4. Modeled brine derived from potash salt compared with N/S brine and seawater . . . .124 Table 2-5. Isotopic fractionation factors for dolomite-water .............................. 131 Table 2-6. Modeled mixtures of Trenton-Black River brine and s e a w a t e r ........................... 141 Table A-l. Appendix A Results of chi-squared t e s t ................ 155 Table A-2. Summary s t a t i s t i c s .......................... 159 Table A-3. Student's t-test r e s u l t s ............ 168 Table A - 4 . Correlation coefficient matrix of log-transformed d a t a .........................171 Table A-5. R-mode factor analysis results ............ ix 189 LIST OF TABLES (cont'd.)* Table B-l. Appendix B Components measured and analytic methods. Table B-2. Variability in 180/160 and D/H . . . . . . Table B-3. Analytic precision and sample comparision. . 226 234 241 Table B-4. Glassware t o l e r a n c e ........................ 243 x LIST OF FIGURES Chapter 1 Figure 1-1. Generalized tectonic map of the Michigan Basin a r e a ..................... 5 Figure 1-2. Paleozoic section of the Michigan basin Figure 1-3. Paleo-geography of the Dundee Formation, from Gardner ( 1 9 7 4 ) .......................... 14 Sample locations ............................. 16 Figure 1-4. ... 6 Figure 1-5. Specific gravity (g/cm3) versus production elevation (m) in the basin. The elevation of the Great Lakes is approximately 180m. . . . .22 Figure 1-6. Br (mg/1) and SO* (mg/1) in the Traverse and Dundee formation w a t e r s ......... 24 Figure 1-7. Ternary diagram showing percentages of Ca-Mg-Na (mole percent) in Michigan basin brines.....................................26 Figure 1-8. Traverse and Berea Formation water chemistry (log mg/1) compared with evapoconcentrated seawater (dashed line, data from McCaffrey et al, 1988; and Carpenter, 1978). Average Niagara-Salina formation water shown as ( O ) A: log Cl-log Br, B: log Na-Br, C: log K-Br, D: log Ca-Br, E: log Mg-Br, F: log Sr-Br .................................... 27 Figure 1-9. Dundee Formation water chemistry (log mg/1) compared with evaporating seawater. Average Niagara-Salina formation water shown as (O ) A: i°9 Cl-log Br, B: log Na-Br, C; log K-Br, D: log Ca-Br, E: log Mg-Br, F: log Sr-Br...................... 29 LIST OF FIGURES (cont'd.). Figure 1-10. Richfield and Detroit River formation water chemistry (log mg/1) compared with evaporating seawater. Average NiagaraSalina formation water shown as ( O) . A: log Cl-log Br, B: log Na-Br, C: log K-Br, D: log Ca-Br, E: log Mg-Br, F: log Sr-Br . . 31 Figure 1-11.(A) Log MC12 (meq/1) vs. log Br (mg/1). (B) Log MCI, corrected for charge balance vs. log Br f m g / l ) Figure 1-12. Figure 1-13. Log MCI, 34 (meq/1) vs. log Cl (mg/1).......... 35 87Sr/86Sr of Michigan basin brines vs. producing formation age. Also shown is the variation of the 8 Sr/86Sr ratio of seawater during the Phanerozoic Eon (Burke et al. , 1982)................................. 38 Figure 1-14. Log MCI, (meq/1) vs. log Br (mg/1) in formation waters of W. Canada, Mississippi, and Illinois basins.......................... 41 Figure 1-15. Results of dolomitization model. Log Ca (mg/1) vs. log Br (mg/1). Filled symbols are measured Ca, open symbols are predicted C a ............................ 4 3 Figure 1-16: Histograms of saturation indices (log lAP/Ksp) for Michigan basin formation waters ............................ Figure 1-17. 46 (A) del D°/oo (SMOW) concentration scale, and (B) del D°/oo (SMOW) activity scale, vs. del 1 0°/oo (SMOW) of Michigan basin waters. Also shown is the best-fit line to the data, and two examples of seawater composition during evapo-concentration, from Holser (1979) and Pierre (1982) . . . . 55 Figure 1-18. del aD°/oo (SMOW) vs. log Br (rag/1) in all Michigan basin waters. Also shown is the best fit line (r2=.8) to the Devonian formation data, and sample M56 from %Clayton et al. (1966) ................ 59 LIST OF FIGURES (cont'd.)- Figure 1-19. Possible mixing scenarios between Dundee formation waters and AMMW. (A) Log Cl (mg/1) vs. log Br (mg/1), and (B) del D°/oo vs. del 180°/oo (SMOW) . . 65 Figure 1-20. del 180 °/oo (SMOW) vs. estimated formation temperature. Shown as a dashed line are the del 180 values for water predicted to be in equilibrium with calcite of -1, -5.75, and -8 °/oo P D B ............... 70 Figure 1-21. Plot of 1/Sr (mg/1) vs. 87Sr/86Sr of the Michigan basin brines..................... 73 Chapter 2 Figure 2-1. Stratigraphic column of the Michigan basin . .79 Figure 2-2. Ternary diagram showing percentages of Ca-Mg-Na (mole percent) in Michigan Basin brines ........................ 81 Figure 2-3. Diagenetic history of Niagaran reefs in Michigan, from Sears and Lucia (1982) . . . . 84 Figure 2-4. Proposed model for freshwater flushing of Niagaran reefs in Michigan, from Gill (1977). Recharge may have entered the Niagaran rocks along marginal arches, flowed down into the basin, and dissolved salt from reefs along the basin margins. . . 86 Figure 2-5. Salina A-l salt stratigraphy, after Matthews and Egleson (1977) . . . 88 Figure 2-6. Sample location map. St. Peter Sandstone sample from (A), and the Case (1945) sample from (B) 90 Figure 2-7. Ternary diagram showing percentages of Ca-Mg-Na (mole percent) in Niagara/Salina and Ordovician aged formations in the Michigan b a s i n ............................. 96 x i ii LIST OF FIGURES (cont'd.). Figure 2-8. Niagara/Salina formation water (log mg/1) compared with evapo-concentrating seawater (dashed lines, data from McCaffrey et al., 1988; and Carpenter, 1978).A: Log Cl-log Br, B: Log Na-Br, C; Log K-Br, D: Log Ca-Br, E: Log Mg-Br, F: Log S r - B r .................. 98 Figure 2-9. Log MC12 (meq/1) vs. log br (mg/1) and log MCI2 (meq/1) vs. log Cl (mg/1) in the Niagara/Salina and Ordovician formation waters, compared with evapo-concentrating seawater (dashed line, data from McCaffrey et al., 1988; and Carpenter, r9TS7— ............102 Figure 2-10. Trenton-Black River and St. Peter Sandstone formation water (log mg/1) compared with evapo-concentrating seawater (dashed lines, data from McCaffrey et a l ., 1988; and Carpenter, 1978). A: Log Cl-log Br, B: Log Na-Br, C: Log K-Br, D: Log Ca-Br, E: Log Mg-Br, F: Log Sr-Br . 103 Figure 2-11. del D °/oo (activity scale) versus del 180 °/oo SMOW in the Niagara/Salina and the Ordovician formation waters, Michigan basin. Also shown is the global meteoric water line (GMWL) from Craig (1969), and the best-fit line to all Michigan basin waters collected as a part of this study................................. 106 Figure 2-12. Result of dolomitization model (log Ca vs. log Br, mg/1) for Niagara/Salina formation waters. Square symbols are measured Ca values, circles are predicted Ca. . . . .108 Figure 2-13. Histograms of saturation indices (log lAP/Ksp) for the Niagara/Salina and Trenton-Black River s a m p l e s ........... 110 Figure 2-14. Log K vs. log Br (mg/1) in seawater brines from the Laguna Madre, Texas (Long and Gudramovics, 1983) ........................ 112 xi v LIST OF FIGURES (cont'd.). Figure 2-15. Calculated del 180 °/oo (PDB) values for dolomite and calcite in isotopic equilibrium with Niagara/Salina formation waters at subsurface temperatures of present-day, present-day+23°C, and 80°C. Bars show range of values from four different dolomitewater fractionation equations discussed in text. Also shown are ranges of del O reported in late diagenetic dolomites and calcites, whole rock (W.R.), A-l Carbonate dolomites, and Niagaran dolomites and calcites in Michigan, from Cercone and Lohmann (1987) and Sears and Lucia (1982) . 133 Figure 2-16. Br (mg/1) in Trenton-Black River formation brines from the Albion-Scipio tre n d ......... 138 Figure 2-17. Cl-Br (log mg/kg) and relative Ca-Mg-Na composition calculated to result __£rom mixing of N/S sample #2099 (point 1) with seawater concentrated to gypsum saturation (point 0). Numbers indicate seawater/brine ratio............. Figure 2-18, 142 Calculated del -*-80 °/oo (PDB) values for dolomite in isotopic equilibrium with Ordovician formation waters at subsurface temperatures of present-day, present-day +23°C, and 80°C. Also shown are ranges of isotopic values for fracture, cap, and regional dolomites in the Trenton-Black River formations, from Taylor (1982) . . . .147 Appendix A Figure A-l, Histograms of Na and Cl (mg/1) concentrations.......... . . 156 Figure A-2. Log-probability plots of Na and Cl (mg/1) concentrations ............................... 157 Figure A - 3 . Average Michigan formation brine composition (log mg/1) compared with seawater (dashed line). Seawater data from McCaffrey et al. (1988)......... .. 164 xv LIST OF FIGURES Figure Figure Figure Figure Figure Figure Figure l—4. (cont'd.)* R-mode factor analysis results (Varimax rotation) from Egleson and Quario (1969) for Sylvania Sandstone formation waters, Michigan Basin ...................... 175 .-5. R-mode factor analysis results from Hitchon et al. (1971), for West Canada basin waters. TOP: varimax rotation, BOTTOM: bi-quartum oblique rotation ............................ 176 .-6. R-mode factor analysis results from Long et al. (1986) for near-surface saline groundwaters in Michigan .................... 178 -7. R-mode factor analysis results, case 1. Only samples with pH variable are used, pH variable included, TDS not partialled out . .................... 199 -8. R-mode factor analysis results, case 2. Ail samples are used, pH variable included, TDS partialled o u t ........... ............... 202 -9. R-mode factor analysis results, case 3. All samples are used, pH variable not included, TDS partialled out ........... 205 -10. R-mode factor analysis results, case 4. All samples are used, pH variable not included, TDS not partialled out ......... 208 Appendix B Figure Figure -1. Alkalinity titration curves, pH vs volume of acid added (ml). Curve A, Richfield brine sample, curve B, Niagara/Salina formation sample, curve C, a near-surface ground water from Michigan.......................... 224 -2. Formation temperature vs. production elevation (meters). Also shown is a geothermal gradient of 23°C/km, starting at 10oc at 33m. Data from Vugranovich (1986)............... 238 xvi CHAPTER Geochemistry of water in Devonian aged formations, Michigan Basin. INTRODUCTION The origin and evolution of sedimentary basin brine has been the 1933; focus Case of et study a l ., White, 1965; Torrey, 1966b; Collins, Carpenter, chemistry interest of 1942; De number Sitter, Collins, Hanor, these because a of years 1947; White, 1982). unique of 1975; Besides fluids, their basin waters involvement in 1985; base-metal mineralization 1982), 1970; (Land, diagenesis (Friedman and Sanders, origin and 1967; Billings Carpenter et a l . , 1974; Cercone and Lohmann, 1987). evolution of 1964), Domenico and Robbins, (Roedder, evaporite-cycling are the of hydrocarbon basin hydrology (Bethke, 1978; understanding (Degens and Chilingar, Bush, 1957; Carpenter, production and migration 1969; (Russell, 1966; Dickey, 1966; Graf et al., 1966a, 1975; 1978; for deep 1985), et al., Long and Angino, 1987), and sediment 1967; Bein and Land, 1983; In spite of this interest, water in many basins the remains unresolved. Any chemical model and for brine isotopic origin must geochemistry of explain the both the water. The chemical evolution of sedimentary basin brine is thought to reflect two, (Lerman, 1970). albeit overlapping, groups of processes First are the concentrating processes that are responsible for the high salinity of these waters, include evaporation, evaporite 1 dissolution, and and shale membrane filtration. Second, are the modifying processes that occurred during the evolution of the water, and include dissolution-reprecipitation, activity, mixing of waters, processes may mask the ion and exchange, shale chemical biological filtration. record of These formation water origin (Chave, 1960). The isotopic evolution of sedimentary basin water may also occur by two general processes. proposed that reflects that rocks, isotopic meteoric composition water has of flushed (1966) basin water through basin and was subsequently modified by exchange with minerals al. the Clayton et al. (Clayton et al., (1964), et al., 1966). Knauth and Beeunas 1969? Hanor, composition of some Alternatively, (1986), rock Degens and others et (Hitchon 1982), have proposed that the isotopic formation water reflects mixing, more specifically, the dilution of evapo-concentrated seawater by meteoric water. isotopic these Hicchon et a l . (1969) values of basin waters processes including suggested that the reflects mixing of a combination marine with of meteoric waters, exchange with rocks, and shale membrane filtration. Several studies have demonstrated these general models and have linked (Carpenter, Beeunas, (Billings 1978 ? brine Stoessell 1986, Dutton, et a l ., chemistry 1969, and 1987), Dressel to Moore, mixed and residual 1983; seawater Knauth and seawater-freshwater Rose, 1982; Spencer, 1987), and freshwater origins (Clayton et a l ., 1966; Hitchon et al., 1971; Kharaka and Berry, 1974? Kharaka et al., 1973; 3 Bassett and isotopic Bentley, evolution 1983). of However, formation the water chemical in many and areas, including the Michigan basin, remains unresolved and may not fit these models. inability to One principle reason for this may be the explain both the chemical and isotopic geochemistry of brine by a single m o d e l . THIS STUDY The Michigan understanding Michigan Similar brine, of other although Michigan of shallow depths have been Beecker, Sorensen al., al. for 1966), Segall, evolution, basin because time (Lane, Ca-Cl The as are they solids have they Egleson 1899; in high Ca exist at Querio, al., 1966; Clayton et a l ., 1966b), their evolution Cook, and 1975; and is Although the Michigan brines 1945; et because brine. dissolved 1945) , they the basins. water however, total and in sedimentary unique (Case, some Case, origin basin role contain Na-Cl having in the basin. Graf important Michigan somewhat mg/1 et 1940; and and formations some studied 1966a; isotopic basins, 640,000 (Graft an inter-cratonic are saline, has brine some brines extremely content both typifies to excess basin rem ins 1914 ; 1969; Graf geochemical to be et and clearly identified. The goal of this study is to determine the geochemical and isotopic chemical and 54 oil evolution of the Michigan basin brines. isotopic composition of brines wells from 6 Devonian producing collected formations The from in Michigan are used, in combination with brine chemistry from Niagara/Salina and Ordovician aged formations in the basin, which are discussed further in Chapter 2. processes for brine evolution evapo-concentration, rock that the brine considered shale membrane interactions. A tenant in each The geochemical include filtration, followed and in this formation may have seawater water- research evolved is through different processes, therefore, the brine chemistry must be evaluated possible) on (whenever an individual formation basis, rather than collectively in a whole basin manner. It became agreement evident exists between evapo-concentrated unexpected, deposits. as early in the this study that Michigan brine chemistry seawater. the basin This is noted Based on this observation, evapo-concentrated seawater brine, reactions in study is used this is for a not its close and totally evaporihe a framework model of modified (Wilson by and water-rock Long, 1986, Wilson and Long, 1987) . STUDY AREA The Michigan sedimentary basin, basin is shown a mature, intercratonic between the Canadian Shield and The the and is outlined by the arches and platforms Paleozoic sediments exist at the deepest point in the Michigan basin, and range from in is occupying an area over 2 00,000 km 2 . located Illinois Basin, Basin Figure Jurassic Paleozoic 1-1. to section Over Cambrian starts 4000m in with of age basinal (Figure 1-2). Cambrian The sandstones CANADIAN SHIELD p-G CHIGAN BASIN V ' M i ILLINOIS BASIN Figure 1-1 : G e n e r a l i z e d area . M P GENERALIZED TECTONIC MAP OF THE MICHIGAN BASIN CINCINNATI ARCH | tectonic map AREA of the M i c h i g a n B a s i n 6 MICHIGAN BASIN E LLS W O R TH 81. PERIOD SUBSURFACE NOMENCLATURE ■ _ "~ r"* ANTRIM 3M. JURASSIC TRAVERSE 0ROUP M A R S H A L L S3 DUNDEE LM S. 6000' ® f ~ ~ D E f R O I T R. BELL SH AMHERSTBURO 3 Y L V A N IA SS. 10,0 00 ' -A -. SILURIAN BOIS B LA N C CARB BASS IS L A N D C A B O T H E A D SM U TIC A SH 1 5 ,0 0 0 ' C A M B R IA N of Figure !_2 ; P a le o z o ic s e ctio n the M ich ig an b asin 7 overlain by Ordovician limestone-dolostones, which are the oldest rocks to exhibit the basin shape (Nunn et a l ., 1934). Over 550m of Silurian evaporites and carbonates follow and include dolomite, anhydrite, halite, and Devonian aged carbonates and evaporites, paper, follow and are overlain by potash the a minerals. focus of this thick layer of Carboniferous to Jurassic aged shales and clastic sediments. The basin sandstones, is estimated to contain 47% carbonates, 18% shales, and Landes, 1955). and 12% evaporites by volume 23% (Cohee Estimated present-day formation volumes (Table 1-1), measured from maps in Gardner (1974) and Curran et al. (1981), indicate that sediment exists in the basin. 7.4xl04 km3 of Devonian aged Assuming an average porosity of 10% and neglecting evaporite layers, the Devonian rocks in Michigan contain approximately 3.5xl016 liters of water. The present approx imately geothermal 22°C/Km (Nunn gradient et al., in 1984), the basin but measured temperatures may vary considerably from this gradient Appendix B). Hogarth (1985) used demonstrate that the paleo-geothermal to the present day gradient, but that conodont (see color gradient was Paleozoic is to similar sediments may have been buried almost 1 km deeper in the past. Other studies have suggested both deeper burial and higher paleogeothermal gradients for Michigan (Cercone,1984). 8 TABLE 1-1 Estimated formation volumes in the Kichigan Basin. AGE& REF. FORMATION OR GROUP________ Km SAMPLED xlO^ ABSOULTE AGE END DURATIO X l O ” XlO^ (1) CARBONIFEROUS GRAND RAPIDS GROUP BAY PORT LMS MICHIGAN FM UNCONFORMITY MARSHALL SANDSTONE COLDWATER SHALE SUNBURY SHALE BEREA SANDSTONE BEDFORD SHALE UNCONFORMITY 46 376 23 399 16 0.46 1.72 0.08 0.08 0.14 (1&2) DEVONIAN ELLSWORTH SHALE ANTRIM SHALE TRAVERSE GROUP TRAVERSE LMS BELL SHALE NATIONAL CITY GYPSUM DUNDEE FORMATION ROGERS CITY REED CITY ANHYDRITE LUCAS or DETROIT RIVER HORNER MEMBER TOTAL HORNER SALTS IUTZI MEMBER MELDRUM TOTAL RICHFIELD MBR. FILER SANDSTONE BOIS BLANC-SYLVANIA 300 1.42 1.20 1.31 0. 04 0.66 0.14 09 53 32 48 18 0.89 9 Table 1-1 (cont'd.). AGES REF. FORMATION OR GROUP Km3 XlO4 SA SAMPLED ABSOULTE AGE END DURATIO X lO ° (1)SILURIAN BASS ISLAND SALINA GROUP G UNIT F EVAPORITE E EVAPORITE D EVAPORITE C CARBONATE B EVAPORITE A-2 CARBONATE A-2 EVAPORITE A-l CARBONATE A-l EVAPORITE BROWN NIAGARAN 0.08 1.46 0.27 0.10 0.17 0.91 0.35 0.84 0.34 0.55 8.79 (1) ORDOVIVIAN UTICA SHALE PRARIE DU CHEIN 0.96 8.88 xlOc 415 26 411 21 .88 * * ★ UNCONFORMITY Key: 1: Curran et al. (1981). 2: Gardner (1974). 3: End and duration of geologic periods in Michigan reported in 106 years, From Nunn et al., (1984). SAMPLED: * indicates formations sampled in this study. 10 Formation waters Sandstone, the reported Traverse on here Group, the are from the Dundee Formation, Detroit River Sour Zone and Richfield Member Formation, and the summary the of thickness, Sylvania general and Sandstone lithology, depositional environments be found Eschman, in Gardner (1974), rocks transgressive-regressive restricted 1974). Matthews in Michigan marine 2) . textures, for Devonian of Door of the Devonian in and (1984). a that the shallow water followed the Silurian (Gardner, The Kaskaskia unconformity is considered the boundary A and (1977), represent sequence conditions 1- Lucas Further descriptions can (1981), and Montgomery et al. Devonian the of the (Figure structure formations is given in Table 1-2. Berea Michigan lower (Gardner, 1974). Overlying this unconformity is the Sylvania Sandstone which represents the start of a transgressive stage of the Early Devonian (Gardner, fluvial 1974) . transported currents sand The which and was deposited carbonates of the Bois-Blanc (Gardner, 1974). The cyclic Sylvania was is reworked concurrent and a by with Amherstburg evaporite-carbonate wind and marine offshore Formations sediments of the Amherstburg and Lucas Formations were then deposited during the Middle Devonian when the basin became restricted. The cyclic deposition is best developed in the Richfield Member of the Lucas Formation, alternating anhydrite which consists and dolomite layers. of over 60m of In the central 11 TABLE 1-2 SPMMARY OF DEVONIAN FORMATION GEOLOGY STRATIGRAPHIC UNIT & MAX. THICKNESS Traverse Group 800' LITHOLOGY STRUCTURE TEXTURE Bio-calcarenite bioherms, biostroms limestone, few wackestones and anhydrite and grainstones and porous dolomites on west margin, gray shale facies on east margin.* Dundee dark limestone with irregular beds and Formation laminar,impure banks, bioturbated 400' anhydrite and wackestones and porous secondary grainstones dolomites on west.* ENVIRONMENT OF DEPOSITION shallow shelf with muddy influx from east. Lagoons on west margin subtidal to shallow shelf, with lagoons, and shabkas on basin margins Horner Member 800' massive salt with interbeds of anhydrite and dark sour carbonates impure dolomitic and layered anhydrites, cloudy-clear salt layering peripheral shabkas and lagoons, and basin centered evaporites Iutzi Member 150' massive anhydrite at base, dolomite and some limestones wide spread at top massive and impure, dolomitic anhydrites and dark micritic carbonates periphal shabkas and penesaline lagoons Richfield syngenetic dolomicrite with Member 100 ' interbedded, displacement anhydrites. oolitic, laminated mudcracks, decussate interclasts, nodular mosaic anhydrites shabka and penesaline lagoons Amherstburg Member 300' Dark, carbonaceous wackestones Bioherms, biostromes shelf to basin, bioturbate, bioclastics, increasingly and pelletal restricted in upper portion. Sylvania 300' White quartzose sandstone, with secondary quartz overgrowths, interbedded with carbonates. cross beds, planar to irreg. bedding, dessication cracks, frosted and polished grains dunes, beach, and bar, open marine along hinge line 12 TABLE 1-2 (cont'd.). STRATIGRAPHIC UNIT & MAX. THICKNESS Bois Blanc 700' LITHOLOGY STRUCTURE TEXTURE Cherty bioirregular to thin bedded calcaranite, mottled wackestone tripolitic chert ENVIRONMENT OF DEPOSITION open marine carbonate shelf silica from adjacent desert land mass * Carbonates are generally limestone on east, and dolomite on south and west basin margins. They are darker and finer grained in basin center. SOURCE: Gardner, 1974 13 basin area the found and Detroit includes River basin deposit carbonates margins as a underlying Salina (Lucas the Horner Member, halite-anhydrite-dolomite Detroit River Group are result salts Formation) a up to (Matthews, later thick 1977) . highly brecciated of 2 00m The around dissolution (Landes et a l ., 1945). is the of the After the deposition of these evaporites and carbonates, a slow return of normal marine conditions occurred Traverse sediments were deposited. of a biostromal found in off-shore extensive margins shales shelf sabkhas during cap deposition the that and Eschman, The areas. and this anhydrite margins, also 1974; 1981; existed and through around the the carbonates suggested 1-3). signal formation the Upper onset that basin Devonian of clastic Carboniferous Matthews, Montgomery especially in mineralogy but also includes chert, generally occur Dundee (Door 1981). sandstone, Eschman, (1974) (Figure and continued Devonian (Gardner, with argillaceous lagoons section the Both formations consist Gardner time calcite and dolomite, quartz facies, and and increase towards lenticular (Montgomery, et al., 1984). dominated anhydrite, Nowak, al., in the 1984). abundance west zones 1978; shales Door and Dolomite near (Gardner, throughout the and basin 1974), the by halite, illitic-chloritic 1977; et is but basin 14 DUNDEE LAGOON OPEN MARINE Figure 1-3. P a l e o - g e o g r a p h y of the after Gardner (1974). Dundee Formation, 15 Oil production from Michigan Devonian rocks has been important since the early 1900's and occurs in a broad band extending (Cohee from and the central Landes, basin 1955; westward Montgomery and et southward al., 1984). Hydrocarbon production occurs from bioherms and anticlines, dolomitized porosity zones, and from fracture related porosity (Montgomery et al., 1984). ANALYTIC METHODS Fifty-four Devonian formation brines were collected as a part of a included waters formations. obtained including larger from on Michigan Silurian basin and brines which Ordovician aged The samples were supplemented with 32 analyses from various Michigan (M.D.N.R.) open Figure 4. study oil company Department file data. and of Sample government Natural locations files Resources are shown Charge balance errors are less than 5%. in Sampled intervals were confirmed by operating personal and drilling records, and by geophysical plugging by salts such, recently those flushing of possible. Well in Michigan and oil-wells is a as common Care was taken to avoid sampling wells that were flushed, located long use when is a serious problem freshwater practice. logs wells near for brine brine from fields disposal under wells. disposal, Sylvania water-flood, Because or of its Sandstone brine was not collected in this study although some data were obtained from M.D.N.R. files. •D U N D E E • TRAVERSE □ RICHFIELD oBEREA • D E TR O IT R. Figure 1-4: Sample locations 17 Samples were collected directly from the well head, filtered through glass wool and Watman #1 paper filters, and stored in pre-rinsed plastic bottles. analysis were collected by diluting Samples raw brine HN03 , using Class A volumetric pipettes. were collected for anion formeldehyde for S04 . D/H, 180/160, analysis for cation 50% with 5% Undiluted samples and preserved with Untreated samples were collected for and 87Sr/86Sr analyses. The pH, Eh, temperature, and when possible, alkalinity, were measured in the field Collins following Lico et (1975) . NBS buffers standardization. Formation a l ., (1982), Wood (1981), and (pH 4 and 7)were used for pH temperature "> were calculated following Vugrinovich (1986) using 10°C at 33m plus 23°C per each km of depth thore-after. laboratory procedures used The components measured and are listed in Table Inorganic analysis was done at the Geochemical Michigan State University. 1-3. Laboratory, Stable isotope ratios (180/ 160, D/H) were measured at the Environmental Isotope Laboratory, University of Waterloo, Laboratories, New Jersey. equilibration distillation Deuterium with Sofer and Gat Argonne were (1975). National and at Teledyne 180/160 analysis utilized 72 hour C02 , and technique values Canada, D/H analysis described in corrected Fritz for et a al. activities 87Sr/86Sr analysis Laboratory. used was Standard (1986). following preformed at chromatography techniques using 2N double distilled HCL and Dowex resin (Stueber et al., 1984) were used to complete (8x-2 00) 18 TABLE 1-3 Components measured and analytic methods. COMPONENT PH Ca, Mg, Sr Na, K Rb, Cs Li Cl Br I B Si n h 4n so4 Alkalinity Density TDS METHOD electrometric flame emmision w / 1 :10 of 87g/l LaClo flame emmision w/1:10 of 25.4g/l NaCl or KC1 flame emmision w/1:10 of 25.4g/l Na-K-Cl flame emmision w/1:10 of 25.4g/l Na-K-Cl Mohr titration colorimetric bromide oxidation colorimetric w/carminic acid colorimetric following extraction potentiometric titration gravimetric potentiometric titration pyconometer @25°C and by calculation SPG=log TDS * 7, 102x10 -7 calculation DILUTION none 1:2000 REFERENCE 1 1 1:2000 1 :26 1:200 none 1:40 1:2 1:10 1 2 1 1 1:200 1:2 none none none 4 5 1 5 + 0.996 References: 1: Brown et al., (1979) Methods for Determination of Inorganic Substances in Water and Fluvial Sediments. U.S.G.S. Water Resources Investigation Book 5, Chapter A-l, Washington, D.C. 2: Presely, B.J. (1971), Part I: Determination of selected minor and major inorganic constituents, in: Ewing, J.I. and others, Initial Report of the Deep Sea Drilling Project, Volume VII, Part 2: Washington, D.C., U.S. Govt. Printing Office, p. 1749-1755. 3: Schrink, D.R., (1965) Determination of silica in sea water using solvent extraction, Anal. Chem., 37, 764-765. 4: Collins, A.G., Cassaggno, J.L., and Macy, V.W. (1969) Potentiometric determination of ammonium nitrogen in oil-field brines, Environmental Science and Technology, 3, 274-275. 5: A.P.I. (1968) Recommended Practice for Analysis of Oil-field Waters, American Petroleum Institute, Washington, D.C., 2nd edition, 58p.. 19 separate Sr. Rb/Sr ratios are <0.001, suggesting that Rb has not appreciably enriched 87Sr. GEOCHEMICAL RESULTS Sample locations, all samples Appendix collected of this ranges, and well data, in and analytic results this report. A concentration study are summary ratios are of listed in geometric listed for the means, in Table 1-4. Total dissolved solids in all samples are in excess of 300 g/1. Sulfate, alkalinity, and pH values reported waters deserve some discussion. for these Sulfate concentrations are very low, much less than seawater values, with some samples having non-detectable S04 . Alkalinity is highly variable, ranging from undetectable values up to several hundred mg/1. Several factors may cause errors measurements. Na For example, poisoning may liquid junction potentials introduce electrode measurements made considerable 1984). and uncertainty in high salinity water and Pytkowicz, 1973; Millero, Dickson, in the pH and alkalinity in (Hawley 1979; Harvie and Weare, 1980; Alkalinity may be also affected by borate and organic acids (Willey et al., 1975). Measurement of the organic has acid successful personal because comm.). found during value of acids content 3.5, of of salinity However, alkalinity perhaps (Appendix these B). a waters interferences slight titrations indicating Eh not (B. inflection near the the of been Fisher, point apparent presence measurements yet of these was pH organic waters TABLE 1-4 Average composition of formation waters COMPONENT BEREA TRAVERSE DUNDEE RICHFIELD DETROI' Cl Br Ca Mg Na K Sr Rb Li B Si 195000 1400 451C0 8250 63000 640 2000 4. 8. 3. 74 12 45 23 315000 2980 3 172000 1100 29000 6600 68200 1660 1060 4. 29. 29 3. 125 50 65 11 282000 1840 30 171000 1000 24500 5100 71000 1640 780 3. 24. 21 3. 110 30 180 10 278000 1660 40 194000 2100 65200 8700 34200 7200 1970 12. 46. 119 2. 230 160 1200 23 296000 4020 13 n h 4n hco3 so4 I TDS MC12 n 212000 3400 88000 11800 23100 13400 2680 38 93 226 2 550 180 10 38 355000 5420 2 Key: All values are geometric means in mg/1. MC12 = Ca + Mg + Sr - 0.5HC03 -S04 as meq/1 n = number of samples analyzed for major components 21 resulted in highly unstable values that drifted considerably with time. Eh most likely and Crooper, Kharaka et 1959; al., controlled by dissolved Fe Back and 1980; Barnes, Stumm 1965; and Morgan, Langmuir, 1981) (Hem 1971; because in non-treated samples, minerals thought to be Fe-oxide or FeS (depending on formation) would precipitate after a few days time. DISTRIBUTION OF BRINE CHEMISTRY Formation waters are often density or chemically stratified in basins, a characteristic that may reflect mass movement or addition, reflect diffusion (Land, spatial variations different geochemical areas of a basin. 1987; in Han o r , brine processes 1984). In chemistry operating might within A summary of the distribution of brine chemistry in the Michigan basin is given here. Figure 1-5 shows the brine density versus production elevation for (specific gravity) all formation collected in this study, including those Ordovician salinity, formations. saline in Michigan sea-level, and brine surface. brine from Silurian and density, and therefore show a only a slight linear increase with depth. Surface elevations above The waters exists as at this shallow range between diagram depths 200 and shows, very (<500m) 300m dense, below land Although the Michigan basin waters appear density stratified, they increase salinity in do not with demonstrate depth the strong characteristic of linear other sedimentary basins such as Illinois (Graf et al., 1966), and (m asl) ELEVATION PRODUCTION 0- . - ? Oo< A BEREA • TR AVERSE o DUNDEE m RICHFIELD A DETR O IT R. □ N IA G A R A / SALINA O O R DO VICIAN 00 -1000 ■ ° s > m wa ■ a J □ -2000 tj_ 1.0 A I.! 1.2 1.3 1.4 SPECIFIC G RAVITY 3 Figure 1- 5 : S p e c i f i c g r a v i t y ( g / c m ) v e r s u s p r o d u c t i o n e l e v a t i o n (m ) in the b a s i n . T h e e l e v a t i o n of t h e G r e a t L a k e s is a p p r o x i m a t e l y 1 8 0 m . 23 the West Canada sedimentary basin (Hitchon et al., 1971). This probably reflects the structural shape of the basin and the fact that samples from different formations collected in a single location in the basin. formation water, cannot be The Niagaran for example, was sampled only from near the basin margins (Chapter 2). Bromide can be used to represent spatial variability in salinity and chemistry of the formation waters. Bromide is selected because the graphical treatment presented below is based on plotting brirs chemistry versus Br, and because bromide is strongly related to salinity (log TDS = 0 .357 * log Br + 4.33, r2 = .85) major elements (Rb, B, and (Cl, and covaries directly with many of the Ca, Mg, K, Sr, I) , deuterium, distribution, in a general and Na) , minor elements 1 ft 0. and manner, Therefore, summarizes the the Br spatial variation of the brine chemistry within the basin. Bromide concentrations data increase towards similar distribution waters, but the the in the combined Traverse-Dundee basin center is suggested limited for data interpretations from being made. (Figure the other prevent 1-6). A formation conclusive It appears that the brine chemistry is related to location and formation depth, with higher concentrations occurring in the deeper, central-basin areas. Sulfate does (Figure 1-6), found follow this but generally in samples basin margins. not collected higher from general distribution S04 concentrations shallower depths near are the TRAVERSE ft BROMIDE .DUNDEE \ • SAMPLE .> l o c a t io n Figure 1-6: Br (mg/1) and T r a v e r s e and D u n d e e ] g / l ) in t h e so formation waters. 25 MAJOR ION COMPOSITION Chloride is the dominant anion in all the samples, as Figure 7 shows, The Berea, either Na or Ca are the dominant cation. Traverse, and Dundee brines are Na-Ca-Cl brine, while the Richfield, are Ca-Na-Cl and water, Sylvania, similar and Detroit River Sour to many of the Zone Niagara/Salina formation brines (Chapter 2). Collins (1975) and Carpenter (1978) demonstrate how formation water chemistry can be compared with evaporating seawater origins brine in order to and evolutions studies (Carpenter, have 1979; and Rose, 1982; The major ion Figure 8 to make of interpretations brine since to chemistry. utilized Rittenhouse, Br/Cl for 1967;Collins, Spencer, 1987; chemistries are 10. as Dutton compared The trend lines 1987; possible A number of this purpose 1975; Dressel and with others). seawater for evaporating in seawater chemistry are from McCaffrey et a l . (1988), which agree well with Black Sea data of Zherebtsova and Volkova (1966) and Carpenter (1978). Also shown are the average compositions of the Niagara/Salina formation water samples from (Chapter 2). The B r ,C l , and concentrated Na in seawater, while and Sr highly enriched over the brines compare well with Mg and K are depleted and Ca the seawater trend. A strong linear relationship exists between log Ca and log Br in the Traverse and Dundee samples (slopes of 0.80 to 0.97, r2=0.77 to 0.78, respectively) r2=0.90 to 0.95). and log Sr-Br (slopes of 1.0 to 1.2, Magnesium also plots linear with log Br, B: BEREA T : TRAVERSE D: DUNDEE RF= RICHFIELD DT:DETROITR. SY:SYLVANIA N /S : NIAGARA/ SALINA 0 : TRENTON/ BLACK RIVER REDT.SY Na Co Figure 1-7 : T e r n a r y d i a g r a m s h o w i n g p e r c e n t a g e s of C a - M g - N a ( m o l e p e r c e n t ) in M i c h i g a n b a s i n b r i n e s . I to (Ti 27 Figure 1-8. T r a v e r s e and B e r e a F o r m a t i o n w a t e r c h e m i s t r y (log mg/1) compared with e v a p o - c o n c e n t r a t e d seawater ( d a s h e d l i n e , d a t a f r o m M c C a f f r e y et al , 1988 ; and Carpenter, 1978). Average Niagara-Salina f o r m a t i o n w a t e r s h o w n as ( O ) A: l o g C l - l o g B r , B: l o g N a - B r , C: l o g K - B r , D: l o g C a - B r , E: l o g M g - B r , F: l o g S r - B r . 28 TRAVERSE & BEREA 5.S B u O 4-5 o •TR A V E R S E J 4 A BEREA _____L J 8.5 B o 5 Z *>\ 0 .4 .5 o \ 4 4.5 C © * 3.5 o> © 3 -1 AA 2.5 5.5 o 5 «_> O 4.5 •if* -I 4.5 5 4 o> J 35 © 3.5 •ii V) o> * • •• j 25 1.5 _L 2 2.5 3 Log B r (m g /!) Figure 8. 3.5 29 Figure 1 -9 . Dundee Formation water chemistry (log mg/1) compaed with evaporating seawater. Average N i a g a r a - S a l i n a f o r m a t i o n w a t e r s h o w n as ( O ) A: l o g C l - l o g B r , B: l o g N a - B r , C: l o g K - B r , D: l o g C a - B r , E: l o g M g - B r , F: l o g S r - B r . 30 DUNDEE 8.6 ----- • e s' o o J 4 8.6 o B Z o -I 4.5 -'" V 4 '' y: 3.5 u» O • •»«••• % • 3 2.5 4.5 o o D» 4 O _l 3.5 Z X jl 4.5 I 4 o> 3.5 ^ 3 5h F e. E 3 •w o J_______ L 1.5 2 25 3 Log Br (mg /l) Figure 9. 35 31 Figure 1-10. Richfield and Detroit River formation water c h e m i s t r y (logmg/1) c o m p a r e d with e v a p o r a t i n g s e a w a t e r . A v e r a g e N i a g a r a - S a 1 lna f o r m a t i o n w a t e r s h o w n as ( ) .A: l o g C l - l o g B r , B: l o g N a - B r , C: l o g K - B r , D: l o g C a - B r , E: l o g M g - B r , F: l o g Sr-Br. o 32 RICHFIELD & DETROIT RIVER 0.5 03 4.5 4.5 AA 5.5 ? 4.5 4.5 3.5 • RICHFIELD 3.5 A DET. R. 2.5 1.5 2.5 3.5 L oq Br lm g/1) Figure 10. 33 but best fit lines have slopes between 0.4 and 0.5 (r2=0.76 to 0.79) . Carpenter (1978) suggested that a further test of formation brine origin would be to compare MC12 with Br and MCI 2 Cl. represents the sum of divalent cation charge balanced by Cl, MC12= Ca + Mg + Sr - 0.5*HC03 - S04 (meq/1). This value carbonates, is not affected by dissolution-precipitation dolomite, approximately sulfates minerals, equals Br saturation is reached, in seawater, or halite. and of MCL2 until carnallite follows the relationship: Log MC12 = Log Br + 0.011 (Carpenter, 1978). with Log MCI2 is compared with log Br in Figure 1-lla, and Cl but in Figure 1-12. The above, the MCl2-Br line data plot for seawater, parallel and suggest to, that an excess of divalent cations or a depletion in Br exists from expected seawater values. Because the MC12 value includes the combined error in measuring five components versus the analytic charge analyses error in balance by measuring adjusting B r , MC12 for was excess corrected charge the (MC12 '= MC12-(EPM cations)+ (EPM anions)), which is shown in Figure 1-llb. An excess of MC12 is still evident in spite of this correction. The log C1-MC12 relationship (Figure 1-12) gives some insight into this excess. similar to the Cl-Br plot the in for MCL2-C1 plot in matching the apparently evapo-concentration than reflects seawater trend, higher are predicted by Although degrees Cl-Br. This most evident for some Richfield-Detroit River brines, of is which 34 MICHIGAN BASIN i— — — log MCL2 (meq/D a ® SEAWATER TREND L OG Br (mg/I) M C I2 (m e q /l) 4 -------1-------1------- 1-------r y y y yO y 25 y % DEVONIAN y' Log ONIAG.-SAL. j_________i 1.5 2 25 3 3.5 1 J L o g Br ( m g / l ) Figure 1-11. (a) L o g M C I ( m e q / l ) vs. log Br ( m g / l ) . MCI corrected for c h a r g e b a l an ce vs. (mg71). ( b) L o g log Br 35 5 .5 * ✓✓ 5h ✓ *✓ * •T R A V E R S E - Log C! ( m g / I ) A B EREA l l _________ S_______ L______ ! ____ _J______ l 5.5 * * / * •D U N D E E f 4.5 5.5 ±1 I_____ I_____ I_____ 1_____ 5 / / 4 ✓ . 5 / i_ A• ✓ r • RICHFIELD O D E T . RIVER 4 1.5 2 2.5 3 3.5 4 4.5 Log M C I2 ( m e q / l ) Figure 1-12. Log MC12 (meq/l) vs. log Cl (mg/l). 36 have MCL2 values identical to seawater concentrated past the start of MgS04 salt precipitation. GEOCHEMICAL ORIGIN As shown in Figures 1-8 to 1-10, a very good agreement exists between the seawater compositions and the Cl-Br and Cl-MCI2 values in these Michigan brines, suggesting that the geochemical seawater. origin of the brines is evapo-concentrated Based on Br concentrations, the Michigan brines have apparently evolved from seawater concentrated from the start of halite precipitation into the MgS04 salt facies. Close inspection of Figures 1-8 to 1-10 shows that some of the samples with lower Br concentrations plot below the seawater This trend line, dilution suggesting appears production depth, as were collected (Figure 1-6). margins related samples Devonian seawater or lower from shallow depths 1-6) might brines have freshwater, with the seawater line. not found in Michigan. brines margins greatly of the dissolution diluted samples with agree well Certainly, the large scale dilution Mississippi Gulf Coast brines Pennsylvania basin shows however, that found in the West Canada sedimentary brines the concentrations CaS04 data been as most Br and found near the basin reflect The diluted. location near the The higher S04 values (Figure have been to well with resulting from infiltration. the they (Spencer, 1987), (Carpenter et a l ., 1974), (Dressel and Rose, 1982) is and not 37 GEOCHEMICAL EVOLUTION While the Cl/Br suggest the brines originated from the evapo-concentration expected of seawater seawater, concentrations the of differences Ca, Mg, K from and Sr demonstrate that the brines have evolved by other processes; most important may be water-rock reactions and mixing. The extent of evolution is illustrated by the 87Sr/86Sr of the brines and results by of MC12 enrichment a preliminary study described of the earlier. strontium The 87Sr/86Sr isotopic composition of the brines are shown in Figure 1-13, where the samples isotopic curve geologic age below, of are from plotted Burke al. of the producing evapo-concentrated Sr, et therefore, reactions with the on carbonates in or (1982) formation. seawater Sr the seawater according As should be these strontium brines to the is discussed almost devoid must other minerals. A reflect generally good agreement exists between the seawater curve and many of the samples, especially for samples from the Richfield and Dundee suggesting that the brines have reacted with Devonian aged carbonates to gain Sr. several facts, seawater Paleozoic. was most important apparently However, This conclusion is tempered by the several the same many times of the samples radiogenic than 87Sr/86Sr of during the (Traverse and formations) curve, perhaps the result of reactions with shale minerals 1984). more that Berea (Stueber et al., are is the seawater Reaction with aluminosilicates is -.7100 .7100 •^SEAWATER ^ RA NG E 0.7090 709 0 •/ v \ 0) « (0 00 e i <9 -.7 0 8 0 / 0 .7 0 8 0 - N \J >_ 0} fCO a 0.7070 0.7060 ■"O— <= m ■** H aa •.7070 .7060 P e n n Miss. 300 Dev. Sil. Camb. Ord. 400 600 500 A G E my. B u r k e et al. (1 9 8 2 ) Figure 1-13: 8 ? S r / 8 6 Sr of M i c h i g a n b a s i n b r i n e s vs. p r o d u c i n g formaxion A l s o s h o w n is t h e v a r i a t i o n o f the Sr/ Sr ratio of seawater during the P h a n e r o z o i c Eon ( B u r k e et a l . , 1982). 39 also consistent with the depletion of K from expected seawater concentrations (Figures 1-7 to 1-9). The enrichment in MC12 over expected seawater values (Figure 1-11) also demonstrates that the brines have evolved from seawater. One explanation might be that MC12 is not enriched, but rather, Br is deficient in these w a t e r s . mechanisms are for example, known that bromide is deplete Br considered from natural conservative Few waters, in evapo- concentrating seawater as it is removed only after potashmagnesia salts precipitate and Krejci-Graf (1963) (Holser, 1979). (in Van Everdingen, that Br and Cl may exchange onto clays. Kozin 1968) (1960), suggested However, the effect of anion exchange on Br-Cl in formation waters is unknown, and it seems unlikely that exchange could noticeably deplete Br from these waters. by the large dilution concentrated brine difference. Finally, required may Although analytical error magnified for the analysis explain correcting decreases the MCl2-Br difference the MCL2-Br difference to from an excess of of for the MCL2-Br charge balance it does not eliminate Therefore, result some of highly (Figure divalent 1-11) it. is assumed cations in these waters, balanced by Cl or anions other than S04~ and C03= . Divalent cation enrichment reactions involving may aluminosilicate or perhaps by shale filtration. from mixing with result MCL2 rich from water-rock or evaporite minerals, Enrichment may also result water from other Although the MC12 enrichment appears large formations. in the Michigan 40 brines it is not uncommon for sedimentary exhibit divalent cation enrichment. West Canada basin waters the Illinois basin brines water to Figure 1-14 shows that (Hitchon Mississippi Gulf Coast brines basin et al., 1971), (Carpenter et al., (Graf et al., 1966) the 1974), and are enriched in MCl2 over seawater. WATER-ROCK REACTIONS Differences between the Ca, Mg, Sr, K, and MC12 content of these brines and evapo-concentrated seawater may reflect water-rock interactions. explain these Reactions differences aluminosilicate reactions, considered include to dolomitization, ion-exchange, mineral diagenesis (Collins, 1975; Land, here and evaporite 1987; Hanor, 1982). DOLOMITIZATION The (Figure strong 1-8 (Collins, to relationships 1-10) 1975; between is suggestive Carpenter, Ca-Br and of dolomite 1978). Mg-Br equilibria Carpenter (1978) demonstrated that an approximate 1:1 relationship between Ca and Br results seawater, rather from than dolomitization from shale by evapo-concentrated filtration (Anderson et al., 1966). The influence of dolomitization on the brine chemistry was evaluated as follows. The difference between Mg in each sample and equivalently concentrated seawater was calculated based on the measured Br in each sample. was assumed to result only This Mg deficiency from dolomitization and so was converted to a predicted Ca concentration based on a 1 for 1 41 W CANADA 3.5 2.5 MISS 3.5 •f IL L IN O IS 8* 2.5 1.5 2 2.5 3 3.5 4 Log Br ( m g / l ) Figure 1-14. L og M C l ^ ( m e q / l ) vs. log Br ( m g / l ) w a t e r s of W. C a n a d a , M i s s i s s i p p i , basins. in f o r m a t i o n and Illinois 42 mole replacement. The predicted Ca are adjusted for CaS04 dissolution, and then compared with the measured Ca in Figure 1-15. Generally, a very good agreement exists between the predicted and measured Ca, suggesting that dolomitization by concentrated seawater This explains suggests that the Ca and Mg in these 1:1 relationship between waters. Ca and Br simply reflects Ca taking the place of the Mg in seawater, which originally co-varied directly with concentration. An interesting Br due feature of to evapo- the Mg-Br relationship is that Mg/Br do not approach 1, as do Ca/ B r . If before Mg depletion and Ca enrichment occurred evaporation, then both Ca and Mg would plot slope of l. The dolomitization Ca-Mg occurred chemistry concurrent, (vs. Br) might with, near a reflect or that after evapo- concentration. If dolomitization concentration, then occurred the concurrent seawater trend with line evapo- for Mg in Figures 1-8 to 1-10 may not truly represent the chemistry of evaporating seawater in carbonate basins. Rather, the paths that Ca and Mg in these brine plot along may represent the path seawater calcite is follows maintained when equilibrium during with evaporation. dolomite and Alternatively, dolomitization may have occurred after evapo-concentration; the more highly dolomitization concentrated brines were and thus show a This may reflect a greater ability greater involved depletion in more in Mg. 43 T3 5.5 4.5 • TR AVE RSE 3.5 A BEREA jlZ 4.5 9 DUNDEE -J 4.5 • RICHFIELD 3.5 A DET. RIVER 1.5 2 2.5 3 3.5 4 Log Br ( m g /l ) Figure 1-15. Results of d o l o m i t i z a t i o n m o d e l . Log Ca ( m g / l ) v s . l o g Br ( m g / l ) . F i l l e d s y m b o l s a r e m e a s u r e d Ca, o p e n s y m b o l s are p r e d i c t e d Ca. 44 of highly saline waters salinity waters have to dolomitize, simply or that the higher interacted to greater (Figure 1-15) extents with formation minerals. The dolomitization model Ca in some samples, samples. Combined measurements may all. especially in the less saline Traverse analytic explain More likely, of error some in Ca, of this Fe-rich from seawater dolomite or Mg-clays by underprediction it may be large. (Ordovician Age) difference, (2CaC03 + but Ca by would the Br not thus formation the Mg Fe = of depleted resulting The Fex in an content of is presently not known, For example, are the reduce mod e l . in Michigan Mg ^ 1-Xj + Both dolomitization, of Devonian dolomites S04 , and Explanations to considered are the CaMgFe(C03)2) or Mg-clay minerals. Fe-rich dolomite Mg, other process have added Ca or depleted Mg from these brines. formation under-predicts but Trenton Formation dolomites reported to contain over 8% FeC03 (Taylor, 1982). To further demonstrate dolomite equilibria, the brine chemistries were modeled using the PHRQPITZ program (Plummer et al., which 1989). uses PHRQPITZ Pitzer's coefficients, is a specific equations for interaction determining following Harvie and Weare (1980). model activity Activity coefficients of Na and Cl are adjusted for temperature, are temperature temperature constants. is invariant considered for in the other adjusting ions. but Only equilibrium The Devonian brines of Michigan are a good test 45 for calculating dolomite equilibria solutions because: coexisting 1) and calcite common brines appear to have been affected by dolomitization, and have been of their in suspected contact with these are the because throughout ionic strength 2) 3) minerals dolomite in high formations, seawater the origin, formation the brines minerals for considerable time. The results of the chemical modeling when the measured pH and alkalinity values are used initially show the brines are slightly saturation dolomite the undersaturated index = -0.71, saturation possible with calcite s2= 0 .80) index=-l.149, errors in pH and and (average calcite dolomite s2= l .357). alkalinity (average Considering measurements, chemical modeling was repeated assuming calcite equilibria. Under this assumption index of 0.017 an average dolomite disequilbrium (s2=0.230) is calculated, suggesting that the brines are in equilibrium with dolomite (Figure l-16a). Strontium over is seawater and similar to that highly enriched follows of Ca a (Figures great contrast to seawater, in 1:1 the Michigan relationship 1-8 to 1-10) . brines with This is Br, in which is devoid of Sr at these levels of evapo-concentration (Zherebtsova and Volkova, 1966). The high Sr content of these brines is probably the result of carbonate mineral reactions which can be evaluated using Sr/Ca ratios. Sass and Starinsky that distinct ranges of Sr/Ca result dolomitization (1979) demonstrated in brines affected by of calcite or aragonite, the transformation 46 40 ! DOLOMITE ANHYDRITE 30 >* o §20 cr a> 10 EL XL j »i "1 "6 -.2 O .2 .6 -3-2-1 LOG lAP/Ksp 0 I 2 3 LOG JAP/Ksp 30 H A LITE 25 *20 . 15 10 a_ -3-2-10 1 LOG lAP/Ksp Figure 1-16: 2 3 Eh. - 3 - 2 - 1 0 1 2 3 LOG lAP/Ksp Histograms of saturation Indices (log for Michigan basin formation waters. lAP/Ksp) 47 POLYHALITE 16 S Y L V IT E I I 12 >* o c a> 3 6 cr ° a> -18 -14 -10 - 6 - 2 2 6 LOG lAP/Ksp -4 -3 -2 -| o LOG lAP/Ksp 24 CARNA LLITE 20 >*16 o c a> g -12 a) XL •12 J] a -9 -6 - 3 0 LOG lAP/Ksp Figure 1-16: Histograms of saturation Indices (lor lAP/Ksp) for Michigan basin formation w a te r6 • 48 of aragonite calcite. to calcite, and solution-reprecipitation of The Devonian formation waters have molar Sr/Ca of 0.01 to 0.023, with values independent of formation. These values agree with the Sr/Ca predicted for dolomitization of aragonite, and calcite. in a few cases, Dolomitization carbonate diagenesis history, before reactions. important the If then solution-reprecipitation of affected aragonite the aragonite suggests brines was early solution-reprecipitation a Sr-rich calcite of precursor that in affected their by other calcite is of was suggested. The use of Sr/Ca ratios to interpret seawater derived brines such as these is somewhat tenuous, however, as these brines would have been associated all phases of diagenesis. with carbonate minerals during The Sr/Ca may therefore, be the sum of the many different reactions that affect carbonates and only appear to reflect the diagenetic reaction involving the largest exchange of Sr. The O *7 Sr/° Sr # ratios presented earlier (Figure 1-13) suggest that these brines may have reacted with carbonates of similar geologic age to the producing formations of the brines. This conclusion is tempered however, because seawater has had similar Sr ratios many times throughout the Paleozoic. Until more data are collected on the Sr isotopic ratios of the basin minerals, such conclusions are tenuous. 49 ALUMINOSILICATE REACTIONS Aluminosilicate mineral reactions may be important in explaining the potassium depletion and the MC12 enrichment. Reactions formation might of include albitization K-feldspar, al., 1973; Merino, 1975; illite, and of plagioclase, chlorite (Kharaka et Land and Prezbindowski, 1981). Authigenic feldspars have been found in carbonate rocks (Kastner, 1979), but have rarely been reported in petrologic studies of personal Devonian c o m m .). carbonate Most likely, rocks in Michigan (Sibley, authigenic K-minerals would be associated with elastics in the basin such as the Berea and Sylvania feldspars clear Berea Nowak (1978) reported in Paleozoic shales of the basin, if minerals. Sandstones. these were considered Authigenic(?) muscovite formation by Sawtelle but authigenic is also (1958). Na it or and K is not primary reported in the Because feldspar abundances and petrogenesis in Michigan basin rocks has not been documented, it is not possible at this point to quantify their effect on K in these brines. Most likely, the formation of illite and the subsequent reaction with carbonates has caused the potassium depletion, for example: 2K+ + CaC03 + 3Al2Si20 5 (O H )4 2KAl2 (AlSi3 )O1 0 (OH)2 + Ca2+ + 4H20 + C02 . Illitic = shales dominate the upper Devonian and Carboniferous rocks, and are present throughout dispersed minerals the section (Nowak, 1978). as discrete Gardner layers (1974) and reports upper Traverse Group contains up to 80% shale in the central 50 basin. The interaction of a K-rich seawater brine with clays may help explain the dominance of illite in the Upper Devonian shales, which are presently at shallow depths m) and low temperatures kinetically (<22°C), conditions unfavorable for the (<500 thought to be smectite-to-illite transformation (Burst, 1969; Perry and How e r , 1970; Hower et a l ., 1976). then the If the shales originated as expandable interaction with K-rich hypersaline explain the dominance of illite in the basin. waters Devonian formations which contain brine than in the Dundee and from the elastics, example, K depletion is greater in the Berea, Sylvania might Illitization is also supported by the depletion of K in brines upper clays, for Trav e r s e , and Richfield-Detroit River samples (Figures 1-7 to 1-9). The reaction given above demonstrates illite diagenesis may be tied into m o d e l , similar the excess to that MC12 . used for An elemental Ca-Mg, balance was attempted to determine if illitization could explain the K depletion and the "excess" Ca this reaction, not explained the depletion produces 1 mole of Ca. seawater large (based on Br) number of still are aluminosilicate reactions amount of K depleted from found to this is diagenesis may much of the excess Ca. During moles of K from seawater follow Generally however, Whether illite dolomitization. is plotted versus the "excess" Ca, exists. suggest of 2 When the samples 2;1 molar relationship. by not excess the predicted an excess of Ca represents clear, explain the a but the other results K depletion and 51 OTHER SALTS The diagenesis of evaporite minerals may important in the evolution of Michigan brines. abundant both throughout near the central-basin the western area Devonian margins (Gardner, the 1974). in basin As be Anhydrite is formations of also an Michigan, and in the example, the "massive anhydrite" layer at the base of the Ituzi Member of the Lucas Formation is over 30m thick and contains some 103 Km3 of anhydrite (Table 1-1). Reactions involving anhydrite or could other evaporite minerals have supplied Ca and possibly enriched MC12 in the basin waters. Reactions to consider include the gypsum to anhydrite transformation and the replacement of gypsum by glauberite or polyhalite. During the gypsum-anhydrite conversion, each lm3 gypsum liberates 0.486m3 of CaS04 saturated water which can dissolve evaporite minerals significance considering anhydrite of that (Borchert this the "massive anhydrite" along with and potential Ca hypothetical layer other Muir, supply more soluble 1964). is The realized transformation from gypsum would have of by the liberated some 7.8X10-*--*- liters of CaS04 enriched water. The replacement of anhydrite or gypsum by glauberite or polyhalite liberates Ca rich fluid by: = Na2Ca(S04)2 (glauberite) + 2CaS04 (H20)2 + 2Na2+ Ca2+ + 2(H20), and 4CaS04 (H20)2 + Mg+ + 2K+ = K2MgCa2 (S04 )4 (polyhalite) + 2Ca+ + 8(H20). Inspection of Figure 1-8 to 1-10 shows that the Na concentrations generally match seawater values, although 52 random samples show a depletion in Na. The Na depletion may reflect glauberite formation, and perhaps ion exchange of Na for Ca. forms Glauberite is not a primary evaporite mineral, during the "breakdown of association with NaCl solutions" Glauberite has yet to be gypsum-anhydrite (Borchert and Muir, reported in Michigan, but in 1964). but it is found in many evaporite deposits such as the Ochoa Series in Texas to (Borchert and Muir, replace (Dellwig, gypsum in 1955) , and 1964). the may, Polyhalite has been found Silurian in part, salts explain observed K depletion in the Devonian brines. reactions water, may not produce large of amounts Michigan some of the Although these of Ca they represent an additional mechanism enriched for divalent cation enrichment (MC12) in brine. In phases, order to determine done routine Plummer et of equilibrium. as saturation Histograms of common Figure 1- 15. in brines indices minerals in attempted other in earlier using (1989), had of indices the by and this the Michigan calcite effect non-carbonate IAP/Ksp) basin study. PHRQPITZ assumed little (log mineral of the minerals. calculated are shown in The model results suggest that the brines may with in addition are al. saturation equilibrium celestite described This assumption calculated be control equilibrium modeling was Modeling was for the to apparently halite, anhydrite, dolomite described undersaturated polyhalite, carnallite, and sylvite. gypsum, earlier. with and The glauberite, 53 MODEL FOR THE BRINE EVOLUTION BASED ON GEOCHEMICAL DATA The chemical data and geologic information presented above suggest that brines in the Devonian Formations of the Michigan basin evolved from evapo-concentrated seawater. Devonian seawater origin history and geology, evaporative is consistent as Devonian rocks conditions. This is with the in Michigan A basin reflect illustrated by the dispersed and bedded evaporite minerals in the basin and by the coastal environments interpreted to have existed in the basin (Gardner, 1974; see Table 1-2). Evapo-concentration of seawater would have occurred in the coastal lagoons located around the basin margins perhaps in stands. the central-basin area sabkhas and (Figure 1-3), and during lower sea level Dense, Na-Mg-K-Cl-S04(?) seawater brine would have refluxed down into the carbonate sediments towards the basin center, mixing with and displacing less dense water residing in the sediments. The more highly concentrated brine would have migrated farther down into the central-basin area as suggested (Figure by underlying trapped the Br Devonian the brine distribution and Silurian and prohibited occurring. Water-rock reactions, after brine the seawater generation composition. dolomitization, aluminosilicate which salt which deeper modified Important diagenesis, beds The would have reflux from occurring both during and then affected 1-6). the the original reactions include Ca, affected Mg, and potassium Sr, and MC12 , and sulfate reduction or precipitation of CaS04 during 54 dolomitization,, which removed S04 . Sulfate reduction is a common processes known to operate in areas such as sabkhas, and may have played a more important role in the basin than previous studies have suggested (Matthews and Querio, 1974). STABLE ISOTOPE RESULTS Figure 1-17 shows the (vs. SMOW) in this study. al. the Devonian The results (1966). D/H and Also shown Craig 180/ 160 isotopic ratios formation waters collected in are similar to those of Clayton et is the global (GMWL) from (1961), during evapo-concentration and up two to meteoric water pathways halite for line seawater saturation, from Holser (1979) and Pierre (1982), respectively. The Michigan brines plot very near the end evaporation trend lines and extend back to the GMWL l-17a). The intermediate Berea, of Traverse, the more saline and Dundee Richfield, of the (Figure samples Detroit plot River, and Niagara-Salina samples and the GMWL (Figure l-17b). The isotopic composition of "apparent modern-day meteoric water" (AMMW) is found where intersect the GMWL. be calculated selected and best fit line to the data Four AMMW values and "basin" lines can (Table if the D 1-6), is Correlation coefficients depending corrected for on the activity show a wide range formation ( 6 a D) . of goodness-of- fit for calculated lines, with the best correlation obtained using £ aD vs. S 180 in Devonian formation water samples only. AMMW values are near estimated present-day average meteoric water falling on mid-Michigan (S180 = - 7 .3°/oo, 6D=-50.6°/oo, (c o n c.) 55 • DEVONIAN SMOW D SMOW • / J del cP® . O N IA G A R A / SALINA □ O RDO VIC IA N / D S M O W (act.) 80 40 i— i— ~i— i— i— ~~i i i t i | i r O BEREA M TRAVERSE ® DUNDEE A RICHFIELD A D E T R O I T R. O N IA G A R A / S A L IN A □ O RDO VICIAN B O ,« 4 -40 * a del -80 -120 -16 Figure 1-17- -12 -8 del -4 0 4 180 S M O W 8 ( b ) del D°/oo (SMOW) concentration scale, lb) and del D /oo (SMOW) activity scale, vs. del 0°/oo (SMOW) of Michigan basin waters. Also shown Is the best-fit line to the data, and two examples of seawater compositions during evapoconcentration, from Molser (1979) and Pierre (1982). TABLE 1-5 Apparent meteoric water compositions. BEST FIT LINE r— ,„AMMW 18 /^a del— 2^0^ del D . n A: del CD = 1.912 del 180 + -34.537 0.46 -7.32 -48.53 40 B: del aD = 3.197 del 180 + -22.909 0. 67 -6,85 -44.82 40 C: del CD = 2.508 del 180 + -33.314 0. 61 -7.89 -53.10 29 D: del aD = 3.489 del 18() + -23.791 0.74 -7.49 -49.93 29 E: del CD = 3.646 del 18() + -38.59 0.79 -11.16 -79.28 26 Equation Key: A: all data, del D on concentration scale B: all data, del D on activity scale C: Devonian formation water data only, del D on concentration scale D: Devonian formation water data only, del D on activity scale E: data from %Clayton et al. (1966), del D on concentration scale AMMW: Apparent modern-day meteoric water, calculated from intersection of best-fit line with the GMWL n: number of samples 57 Long et al, 1989). Also listed in Table 1-6 is the equation for the best fit line from Clayton et al. Clayton et al. used samples mainly from the Devonian formations, their calculated However, (19966) for line is Devonian similar to samples the Clayton et al. the from (1966) (1966) . Because best-fit this present lines study. line intersects the GMWL at slightly more negative values than present-day meteoric water. INTERPRETATION Based partially on the §D-S180 values in Michigan basin brines, had Clayton et a l . (1966) flushed the basin argued that meteoric and that Michigan brines part, by shale membrane filtration. waters formed, in A meteoric water origin was suggested because the best fit line to the isotopic data intersects the precipitation calling GMWL at falling a on SD value Michigan. for the evolution of similar Their freshwater and to modern-day model however, seawater into brine, is not consistent with the evaporated seawater origin interpreted from the chemical data in this present study. Knauth and composition of dilution of evolution Beeunas many (1986) sedimentary evapo-concentrated of meteoric proposed water that basin seawater into brine. the brines rather The isotopic reflects than the isotopic composition of seawater first apparently increases in D and 0 during evaporation until approximately gypsum saturation is reached (4x concentration). the isotopic values decrease; With continued evaporation due in part to back exchange 58 with the atmosphere and changing H20 activities. The isotopic composition of seawater after halite saturation is reached (lOx concentration, lines in Figure 1-17) and may be highly near the end of the evaporation is however, variable. generally not predictable The dilution of a residual seawater brine by AMMW then causes formation waters to plot along the best-fit "basin" line (Knauth and Beeunas, 1986). The isotopic composition of the Michigan brines may be explained by Knauth and Beeunas (1986) model. Perhaps the best evidence for this is the lower salinity of the samples plotting close to the GMWL. This is demonstrated by Figure 1-18, which shows £ aD plotted versus log Br (mg/1) for the brines strong linear collected relationship conservative in this (r2=0.8) study. that components The exists shows that between these samples with negative &D values have lower Br and salinity. this and the spatial distribution shown in two more Considering Figure l-6a, water with lower Br and more negative D values are produced from near the basin margins. the isotopic data for the Thus, at first consideration, Devonian brines are consistent with evapo-concentrated seawater that has been diluted near the basin margin by member waters infiltrating meteoric water. and the extent entirely evident. The end of dilution are however, not (a c t.) del D %oSMOW • DEVONIAN ✓ - 160 0 1 2 o M5 6 O NIA G .-SAL. 3 4 Log Bfi (mg/i) Figure 1-18 . del D /oo (SMOW) vs. log Br (mg/1) in a l l Michigan ba^in waters. A l s o s h o w n is t h e b e s t f i t l i n e ( r = . 8 ) to t h e D e v o n i a n f o r m a t i o n d a t a , and s a m p l e M56 from % C l a y t o n et a l . (1966). 60 DISCUSSION Although the Knauth and Beeunas model is accepted here, an inconsistency occurs in that while the isotopic data may represent dilution, the chemical data apparently does not. If dilution has been masked in the Cl and Na data shown in Figures 1-8 between Br to 1-10, and Ca, then Sr, the Mg, co-varying K, and MC12 relationships may represent dilution and not enrichment by evapo-concentration. is indeed the case, the upper formed by composition then the isotopic data might show that Devonian brine dilution of of If this (Berea, saline around Traverse, water 6 D=-20°/oo, having Dundee) an $ 180=2°/oo, some of the more concentrated Richfield, Niagara/Salina brines. and isotopic similar to Detroit River, or In other w o r d s , the brine in upper formations of the basin may have evolved from water derived from deeper formations. agreement between Two explanations for the lack of isotopic and chemical data are possible, either the isotopic data do not represent dilution by AMMW, or halite equilibria has removed dilution from the Na-Cl data. chemical evidence of Failure for the isotopic data to reflect dilution might mean the isotopic composition of the brine is primarily that of evapo-concentrated seawater, or alternatively, the components expected to behave conservatively during dilution (D,0,Br), in reality, do not. In order end to explore member waters, these both questions saline further, and the AMMW possible must be characterized, and the question of what would be required to 61 link the chemical and isotopic data together must be addressed. SALINE END MEMBER In contrast to composition difficult of its chemical the to saline end quantify. composition, member The water isotopic the isotopic (seawater) composition is of evaporating water is a function of the initial composition, humidity, rate of evaporation, phase, and degree of mixing isotopic values in the vapor (Lloyd, 1972 and 1975; Nadler and Margatiz, complex interplay of these 1966; Sofer 1980). factors, the and Gat, Because of the isotopic path of seawater during evaporation may be unique for any basin, and may vary within a basin. This variability is demonstrated by the two different evaporation paths shown in Figure 1-17, and by the results of Nadler and Magritz the isotopic evaporation. saturation, scale) composition Their brines data Mediterranean show that after seawater during reaching halite residual seawater brine had a 8 D composition seawater of (1979) who measured source. are precipitation more negative Considering concentrated (lOx), far very than that past little the most the can (concentration non-evaporated of the start be said of Michigan halite about the isotopic composition of the parent seawater bitterns for the Michigan brines. seawater before present-day SMOW. Additionally, evaporation may the have isotopic been It has been suggested, values of different from for example, that seawater may have been 1 to 2°/oo lighter in lsO during the 62 Devonian (Fritz, 1971; Popp et a l . , 1986). A change of this magnitude in both £ 180 and S D would make Devonian seawater plot very near the main group of Michigan brines in Figure 1-17. Thus, the isotopic composition of Michigan basin brines may be nearly that of the parent seawater from which they were derived, seawater brines or were alternatively, diluted with if Devonian concentrated seawater, then dilution may not be visible in the' isotopic data. APPARENT MODERN-DAY METEORIC WATER The isotopic and chemical nature of AMMW must also be considered. must have A wide variety of meteoric water fallen on the basin throughout compositions geologic time. Thus, the chemical and isotopic composition of AMMW may not be that of "modern-day11 meteoric water. between D and Br AMMW (Figure 1-18) composition. considered deuterium may enriched by exchange organic in with matter Hitchon and Friedman, 1969). v s with a . S 180 SD of (Table -50°/oo, 1-6) . clays, decay water is generally waters, (Fritz although and et may a l ., The best fit line to the br 1986; D-Br =.8), somewhat better than This line predicts (Table that AMMW 1-6) , should (525 mg/1 using the concentration The source for a Br enriched meteoric water of this composition is unknown. a Br, gases, the AMMW value contain about 450mg/l Br scale). like formation data shows a good correlation (r for SD relationship can be used to help evaluate Deuterium, conservative The by salt To evolve meteoric water into such dissolution, saturation with halite 63 containing uncommonly high concentrations of Br is reguired, in this case, at least 1260ppm Br. describe halite recrystallization Recent models that (Stoessell and Carpenter, 1986) and the effects of diffusion during the interaction of saturated (Wilson brine and with Long, halite 1985), may but explain the Br enrichment occurrence of these processes in natural systems has not been demonstrated. The D-Br line negative 6 D meteoric water, This value rather values is than isotopically (Figure not in 1-18) at Br low example, light taken values of is back when water. also the derived by fit line of water Infiltration supported best very Br=lmg/1. sample from Clayton et a l . (1966), determining to characteristic glacially meteoric water extends 8 D=-195°/oo characteristic present-day 1-18) used for (Figure of M56 which was sho w n . This Traverse water sample was collected at the extreme western edge of the basin meltwater (18N, 17W) (gD=-109 °/oo, S 180 = -13.11 which had dissolved halite minimum) (Graf et best-fit line, al., and is thought to be glacial (115 g/1) 1966). suggesting °/oo, Br= 134 ppm) and anhydrite (3.6 g/1 Sample M56 that dilution light water causes the D-Br relationship. member water has a more negative plots by near the isotopically If the dilute end isotopic composition then AMMW then a much smaller amount of meteoric water is needed to explain the isotopic trend, which may help explain the lack of dilution in the Cl-Na d a t a . 64 LINKING ISOTOPIC AND CHEMICAL DATA Considering the problems involved in defining the chemical and isotopic compositions of the end member waters, it may not be possible to link together in a single model. would be required if the the two types of A question therefore, two types of data data is what represent the same evolutionary path? This question is explored in Figure 1-19, where, because the isotopic composition of the saline end member is not known, the following model was considered. Two Dundee formation water samples (water A, #3029, and water B, #3081) are used, along Table 1-5 collected with apparent meteoric water (AMMW) The composition of these two samples, which were from the basin center and margin, respectively, and various mixtures are listed in Table 1-6. of a from single saline end member by AMMW If dilution explains these samples, then continued dilution of sample A by AMMW should account for the chemical intermediate sample B. and isotopic composition of the Bromide and deuterium are the only elements that can be considered conservative in mixing, as Cl could be supplied by halite dissolution and 180 could be altered by reactions with carbonates and other minera’s. First, the deuterium in sample B is predicted based on dilution bromide. of sample Based (Br=0) predicts Figure l-19a on A, B r , the that after with a dilution sample 50% dilution mix B would of calculated sample plot at h by point using AMMW C on (Br=640mg/1, Cl= 9 2 ,500mg/l). 65 2 2.5 3 3.5 Log Br (mg/l) xA AMMW ®— B -100 -15 0 5 del 1 8 0 (SMOW) Figure 1-19. PoBBible mixing scenarios between Dundee brines and AMMW. (A) Log Cl ( m g / l ) v s . log Br ( m g / l ) , and (B) del D /oo vs. del 0 ° / o o (SM OW ) 66 TABLE 1-6 Results of nixing example. POINT SD Cl S'J^ O c Br 1.06 1240 185.000 6.21 620 92.500 C -39.6 -35.8 -3.53 -3.42 (not corrected for brine salinity) 620 158.000 0.5 C -39.6 -3.53 (corrected for brine salinity) 620 92.500 0.5 D' -52.7 -52.6 -7.76 -7.73 (not corrected for brine salinity) 22 3330 0.18 D -52.6 -7.76 (corrected for brine salinity) 19 2775 0. 15 A -26.1 (sample 3029) -18.6 0.43 B -52.6 (sample 3081) -48.6 -6.53 - AMMW -4 9.9 -7.4 9 (activity scale from line D, table 5) variable AMMW -53.1 -7.89 0 (concentration scale, from line C, Table 5) variable Key: Br and Cl as mg/l, del D and del 180 as °/oo, SMOW. Point C = composition resulting from dilution of Br jo Dn= composition resulting from dilution of D E°ink 'D, “ O = deuterium and oxygen on concentration scale. aD, 180a = deuterium and oxygen on activity scale. f = fraction of brine sample A in mixture, 1-f fraction of AMMW in mix. 67 Point C clearly does not match sample B in Cl, but if AMMW had dissolution dissolved 63.5 g/1 halite, or if halite occurred after mixing to increase Cl to 131,000 mg/l, both Br and Cl in sample B can be explained. shown in Figure l-19b, S180=-3.22°/oo in (concentration • enrichment S cl80 over 1Q of S o However, as the mixture has a 6 cD=- 3 9 .6°/oo and scale, activity following Sofer and Gat, enriched than by water S 180 1972), B. which Whether , mineral carbonate corrected from is 3 permil this reflects , reactions is discussed below. Next, the Br in sample B is predicted based on dilution of sample A, with dilution calculated using deuterium. calculating the isotopic and dilute water, composition of mixtures of When brine it is important to recognize that a given volume of a highly concentrated brine contains significantly fewer water molecules example, than the same amount a liter of brine A contains about molecules in a liter of pure water. of AMMW. For 7 0% of the H 20 Consideration of this is made in the isotopic mixing calculation by using: F* A * ( Dbrine)+ (1-F)*i*( Dfreshwater)= where F is the fraction of brine mixed, of water compared molecules with in freshwater the and A is the ratio concentrated (water Dmix molecules brine per solution kg brine solution / water molecules per kg freshwater). The value of A in AMMW is assigned 1. The results of calculated mixing considering this factor are listed in Table 1-6. 68 The mixing of 15% sample A with 85% AMW can predict the S CD in sample B. Because sample B does not fall exactly on a straight mixing line between sample A and AMMW, sample B can be matched only in 8CD, and only approximately matched S180. This mix plots at point D in Figure l-19b. point D plots jpD=-52.6, in Figure l-19a at S c 180= - 7 .76°/oo). in However, Br=19mg/1, Cl=2775mg/1 Because the final would depend on the amount of halite dissolved, Cl ( content the mixture 9 may plot mixture anywhere chemistry along the would line reflect D-D . In this case halite dissolution, the and clearly does not match the composition of sample B. In sum, Br and &CD it does not appear possible to predict both the in sample B by using a single Similar results are obtained when mixing mixing samples that have SCD more intermediate between sample A and AMMW, is noted that the closer the water is to sample A, ratio. however, it SCD value of the intermediate the closer the agreement becomes with dilution based on Br. These calculations suggest that if dilution of a saline end member brine, water by AMMW explains the Devonian as suggested by the isotopic data, formation then it must have been accompanied by halite dissolution and 180 enrichment. Halite considering dissolution is certainly presence of halite in the basin, possible, the and the geologic evidence that Salina salts were extensively dissolved from around the basin margins 1945). The during next the Devonian consideration, time therefore, (Landes et is whether al., 180 69 enrichment has occurred . minerals. (1966), from reactions with oxygen bearing • 1Q Enrichment of xo0 was proposed by Clayton et al. who suggested that isotopic • I carbonate minerals causes the Q , g o m equilibrium , with , brines to shift the meteoric water line (Figure 1-17). from Hitchon and Friedman (1969) calculated that West Canada formation waters may have been enriched by as much as +9°/oo in equilibration demonstrated • increase Knauth with that pore-waters 1 xo0 during ft m and Beeunas formation waters Isotopic versus in (1986) estimated in carbonates Land (1980) will rapidly show how 180 enrichment and of from gypsum dewatering as well 1986). equilibrium Figure rocks. mineral re-crystallization, can result (Knauth and Beeunas, evaluated carbonate S180 as a result of 1-20, formation with carbonate where S180 values temperatures. minerals are Data is plotted on the isotopic composition of Devonian carbonates in Michigan are severely lacking, however, Gardner (1974) reports an average 180/160 of -5.75°/00 Detroit River Group. Clayton et calculate al. water (PDB) for micritic (alpha) from the This values is similar to that used by (1966) (-5.39°/oo PDB) and can be used to 1o t § 0 as a function of temperature using: alpha* < S18°rock+100<» = < 6 18‘W e r » ' 1°°0 > • factor calcite is calculated using: - 2.89 , from O'Neil and Epstein The fractionation 103ln alpha=2.78xl06T-2 (1966). Figure 1-20 shows the brines exhibit a wide spread of 180/ 160 ratios over the narrow range of formation temperatures, and plot across the 70 - I P D B ,,' -5.75 _ . PDB^ / / / □ / £ o r- □ A s /°A t/> 0 o -2 v (X> Q) ° -4 / / V

_ CO \ I :o o ' , .709 J V \ oo o K\m v># I ' *.< .708 (A .707 i i i t _| 5x10* I ■ ■ I j i i i r3 1x10 1 /S r(m g /I) Figure 1-21: P l o t of 1 / S r ( m g / l ) v s . M i c h i g a n basin brines. i 74 having similar isotopic values independent of Sr concentration. (0.7082 to 0.7092) One interpretation is that this diagram does show dilution of a Richfield-Detroit River or Niagara/Salina formation brine,by a dilute water having a isotopic ground composition water in similar Michigan to may the have brine. these Near-surface characteristics because their Sr composition would be governed by reactions with Paleozoic example, carbonates in the bedrock and t i l l . Lake Huron water ratio of 0.7086 is reported to have an a 87Sr/86Sr (Faure et a l ., 1963), similar to many of the deep brine samples reported here. by water-rock reactions, (McNutt et al., As Enrichment in 87Sr caused especially those involving shales 1987; Stueber et al., 1984), may explain the dispersion from a linear mixing trend. Several other observations lend support to a evolution for the upper Devonian formation brines. it is questionable that evaporative mixing First, conditions in the Traverse and Dundee formations ever reached the high degrees needed to explain the Br in the brines. Conditions that favor seawater evapo-concentration into the late halite and MgS04 salt facies is certainly more consistent with the Salina geology in Michigan. Additionally, the Niagara-Salina and Richfield-Detroit River formation waters are highly enriched 1-11, Chapter 2). in MC12 (Figure Although the mineral reactions discussed previously might explain some MCl2 enrichment, especially in light of the enrichments found in other basins (Figure 1-4), 75 dilution of a MC12 enriched brine derived from the Silurian salts is also possible. Based volumes listed in Table 1-1, on the measured formation fluids representing less than 10% of the present volume of Silurian salts can account for the volume of Devonian porosity of Silurian salts compaction 10%). Any that may formation waters remnant has have brine migrated caused the (assuming squeezed upwards MC12 average from during sediment enrichment. These fluids would have mixed with dilute waters present Devonian sediments, margins. or were later It is not known however, have moved upwards compacting basin suggests a to diluted near as to basin if such dense brine could Michigan (Bethke, modification in the the the Devonian sediments in such the a slowly 1985), which this scenario. The MC 1 2 enrichment may have simply been carried along through time with each not based incursion of on suggested remained chemical that in seawater the highly into the basin. evidence, Briggs concentrated central-basin are resided Devonian. in the lower areas of al. seawater of incursions of seawater in the Silurian. have et Although the (1980) bitterns Michigan between Similar fluids may basin during Burial and compaction may later move the the fluids towards the basin margins, mixing with meteoric water. SUMMARY The data presented here suggest that Devonian formation brines in seawater. Michigan This is originated supported by from the evapo-concentrated halide chemistry, as 76 well as by relationships between the other elements and Br. Although somewhat dilution of meteoric more an equivocal, isotopic evapo-concentrated water. The original data seawater support bittern evapo-concentrated by seawater chemistry was modified by extensive water-rock interactions. Most important appears to be dolomitization and aluminosilicate reactions such as illitization. Two scenarios are presented to explain the chemical and isotopic with origin. Devonian from the Either the brines formed formation rocks or they underlying Detroit River, formations, are such or Niagara-Salina. syngenetically in part derived as the Richfield, The data do not seem to unequivocally distinguish between these origins. Several favor a chemical syngenetic formation water, important degree are of the Sylvania-Detroit suggest an brines. evolution difference concentration in conditions observations for the however, upper Devonian in reached cation by Most composition the upper and Devonian (Dundee-Traverse-Berea) brines, versus the underlying River waters Silurian). evolution similarity (Sawtelle, formation and independent The geologic and make this the preferred m o d e l . the formation brines water and in 1958) for These these chemistry suggests and that (Richfielddifferences two lack Berea groups of evaporitic Formation waters perhaps migrated from the upper Devonian formations. The fact (Richfield, that the lower Detroit River) Devonian formation brines are more highly concentrated Ca- 77 Cl solutions that have similar isotopic compositions that do not suggest dilution, and are associated with Devonian and Silurian evaporite deposits supports that these waters share a common origin, possibly being remnant brine derived from the evaporite deposits. In the syngenetic origin model, the brines originated during deposition of upper Devonian formation sediments in coastal sabkhas and lagoons as well as during restricted periods of the Devonian. Dense seawater brines would have refluxed down into the lower areas of the basin and reacted with the layers formation would downward. isotopic have carbonates kept The brines composition, the and clays. brines from Underlying refluxing further largely retain their parent perhaps being modified by salt seawater carbonate equilibria, and some were later apparently diluted to minor degrees with meteoric water. In the second scenario, Devonian formations originated, from the Divalent lower Devonian cations in the or the brines in part, perhaps fluids would in the upper from fluids derived the Silurian have been salts. enriched either as the result of the reactions suggested earlier, by reactions involving the Silurian potash deposits. fluids would have moved compaction and mixed into the or These Devonian sediments during with meteoric water. In this case, the diluted bitterns have maintained equilibrium with halite and carbonate rocks. CHAPTER 2 Origiii and evolution of water in Niagara-Salina and Ordovician aged formations, Michigan Basin INTRODUCTION Sedimentary basins contain a variety of sediment types reflecting many geologic histories, and as such, no single rock type or diagenetic history will basin. Similarly, characterize a single it is possible that no single origin or evolution can explain the chemistry of all waters within basin. with Although sediments formation water and chemistry may evolve mixing, the water by of a basin may retain a chemical by a reactions within signature reflects an origin or evolution unique to the basin. each that This suggests that to best determine their geochemical origin and evolution, basin waters should be studied on an individual formation basis whenever possible. The Paleozoic rocks in the Michigan basin reflect basin, the many geologic conditions that (Figure 2-1) existed in the such as periods of shallow and deep water carbonate deposition, deposition, hyper-saline evaporite and periods of emergence. deposition, clastic The origin of saline waters contained within the basin has been linked to periods of intense seawater evaporation (Chapter 1). Under a more detailed examination however, differences in water chemistry are observed between the individual formations of the basin. Figure 2-2 illustrates the the major cation composition of 78 79 MICHIGAN BASIN PERIOD SUBSURFACE NOMENCLATURE JURASSIC A-2 CARB. P E N N SYLVAN IA N M ISSISStPIAN A-2 SALT M A R S H A L L SS E LLS W O R TH ANTRIM f w B E R E A 8S A -l 6000' TR A V ER SE CROUP D E V O N IA N is ® B E L L SH DUNDEE Fw OET. R IV E R CRO UP NIA6ARAN S YLV AN IA SS C A B O T H E A D SH, M A N IT O U L IN P O L . 10,0 0 0 * S A L IN A S IL U R IA N A -2 GROUP RICHMOND •A* I U T IC A O RDOVICIAN SH CABOT HE AO SH C Q L H N CWQQD j UTICA SH TRENTON BLACK RIVgR H. TRENTO N B LA C K RIVER P R A IR IE DU C H IE N St. PETER SS 1 5 .0 0 0 * PRARIE du CHEIN CA M BRIAN Figure 2-1. S tra ti g r a p h ic column of the Michigan basin. 80 brine from chemistry the different formations in Michigan. in the basin ranges between Na water as a function of formation. Brine and Ca dominated These differences reflect the different evolutions of the water within each formation, and might be explained by formation history, mineralogy, hydrology, and geochemical reactions. This paper Ordovician and basin. These history, and chemistry. reports Silurian on formation aged formations formations as Figure Silurian differ 2-2 in waters in the their demonstrates, reefs reduce and their are and CaCl2 brine known Michigan in their and water formations produced water mainly encased hydrologic formations, the geology Niagaran aged reefs that encircle the basin. buried in produced in of 1945). the In These deeply that connection some (Case, salts significantly with most from overlying highly contrast, saline Ordovician aged Trenton and Black River formations produce water from a major fracture system in the basin, at shallower depths than, the located outside of, Niagaran reefs. and The Ordovician rocks in this area are not capped by the Salina salts and the fault system allows ready connection to other formations. that being is These Ordovician formations contain NaCl brine less more saline similar than to formations in the basin the water Niagara/Salina from (Figure 2-2). the formations, upper Devonian This paper proposes that water in the Silurian and Ordovician formations of the Michigan basin originated from evapo-concentrated seawater, B : B EREA T : TRAVERSE D ! DUNDEE R F : RSCHFIELD D T :D E T R O IT R . S Y :SYLVANIA N / S : N IA G A R A / S A L IN A 0 : TRENTON/ BLACK RIVER Ca Figure 2 2. Na T e r n a r y d i a g r a m s h o w i n g p e r c e n t a g e s of C a - M g - N a ( m o l e p e r c e n t ) in M i c h i g a n B a s i n b r i n e s . 00 82 similar to the origin proposed for water in other formations in the basin (Chapter 1) . Both formations retain unique chemical signatures, however, the Ordovician formation brine suggests an formation their evolution water by mixing, retains seawater a origin while chemical and an the Niagara/Salina signature evolution reflecting by water-rock reactions. STUDY AREA NIAGARA/SALINA REEFS Formation waters studied here are produced from middle Silurian aged Niagaran carbonate reefs (Figure 2-1). Because the reefs are built upon the Niagaran dolomites and intersect the Salina the true producing Therefore, brines. these 5000 1979). formation samples Three the reefs with acres, diagenetic and mostly Carbonate unit within of the water are termed They salts, in question. Niagara/Salina individual averaging reef are have highly 80 acres been criteria located nearest water, about types geologic reefs occupying (N/S) is located contain more (Gill, porosity plugged with innermost pinnacle dolomitized, and salt. reefs size 1979). and and have The which is only First have on are contain little or The second reef less dolomitized. minor third group contain (Gill, based the basin margins which basinward hydrocarbons in from <1 to identified none of their porosity plugged with salt. group is the Niagaran reefs encircle the basin in a belt some 16 to 40 km wide, over A-l mostly amounts includes gas or of the are 83 barren, are slightly dolomitized, and in some cases, their porosity is completely plugged with salt. REEF HISTORY The Niagaran reefs have interacted with water types during their history Friedman, 1977; Gill, 2-3 outlines the (Fisher, 1977; 1979; Sears and Lucia, Nurmi 1980). Reef Niagaran Lockport of and Figure reef history and is from Sears and (1980). Lucia growth began after deposition of the Middle Formation carbonates, stable ramp platform in the basin (3-1). the a variety shallower basin margins, in deeper water as pinnacle reefs. which formed a Reefs formed along mid-shelf areas, and During reef growth, in frame building organisms that formed the bulk of the reefs built upwards in response to rising sea level. Sometime about 45m, after seawater Dolomitization isolation pinnacle levels of the during this period basin the reefs lowered reefs is reached heights exposed the and occurred by a mixed water system (3-II). Extreme during which to reefs. have followed thought time concentrated seawater interacted with the reefs as the Salina A-l were deposited around the reefs in sea level and deposited first base (3-IV). two stages, levels, and (3-III). conglomerates over the of salts the and stromatolites, A-l Carbonate later salts A subsequent rise allowed thinly laminated algal mudstones, of around to the be reef The A-l Carbonate was apparently deposited in over the reefs during the periods inter-reef during lower stands. of high Tidal sea flats 84 o . I n REEF GROWTH EXPO SURE AND D O LO M lTIZATlO N IN M IXING ZONE o 7X AI I R fS T R /C T fD * A * * £ "*0*[RC*P°' * { F l UX «7* m BPIHf ftA T ! DEPO SITIO N OF A -l EVAPORITE AHnrt)*!T£ 12 D E PO SITIO N OF A -l CARBONATE OVER REEFS AND IN IN TE R -R E E F AREAS amtrDRift rJ O d i F IA T SA LT S A T UR A T CD ZJ£0K~ ~ T 7 2 DOLOMITIZATION BY REFLUX FROM A-l CARBONATE TID A L FLAT 3ZI S a lt m Figure 2-3. DEPOSITION OF A-2 EVAPORITE S a tu ra tc d BRmcs COMPACTION AND SALT PLUGGING D i a g e n e t i c h i s t o r y of N i a g a r a n M i c h i g a n , from Sears and Lucia r e e f s in (1982). 85 formed during low dolomitization inter-reef seawater of the areas stands and resulted upper portions of the by refluxing seawater in reefs and the brine (3-V). Following this, the A-2 and ensuing Salina salts buried the reefs Salt (3-VI). saturated brines are thought to have infiltrated the reefs during the deposition of the A-l A-2 salts (1977) (3-VII) and suggested deposition of during that the A-l salt compaction. concentrated salts was McCollough seawater responsible and from the the salt for plugging of porosity in the Niagaran ree f s . Although a variety of waters, during their early history, interacted with the reefs including fresh-water, normal marine, and hypersaline seawater, fluid movement through the reefs occurred later as w e l l . Gill freshwater entered the Niagaran (1979) suggested rocks at the basin margins sometime during the Late Silurian to Middle Devonian and flushed the outer 2-4) . After migrating reefs fluids that and cements, equant temperature filling salts hydrocarbons were became time, (Figure removed, up-dip entrapped in the In addition, Cercone and Lohmann (1987) late (geopetal reefs opening their porosity pore (Gill, 1979). reported reefs the that burial diagenetic sediment, pyrite, calcite (>80°C) spar) deep formed basinal assemblages bituman, as a brines result that in the dolomitic of high migrated through the Niagara and the A-l Carbonate formations. SAL T PLUGGED Woter too concentrated to d i i s o l v a PARTLY REOPENED REOPENED R E E F S RECHARGE 1 LOCKPORT 2 S A L I NA A - l 3 S A L I N A A - 2 SALT 4 S A L I N A GROUP hal i t e WATER F LOW Figure 2-4. Proposed model for freshwater flushing of Niagaran reefs in M i c h i g a n , from Gill (1977). Recharge may have entered the Niagaran rocks along marginal arches, flowed down into the b a s i n , a n d d i s s o l v e d s a l t f r o m r e e f s a l o n g the bas in m a r g i n s . 87 SALINA SALTS The Salina salts, especially the A-l salt, may play an important brines. role in the generation of the Over 500m of Salina salts exist Michigan Basin in the Michigan basin in 6 individual units (the Salina A to F salts) . salt origin has been linked to the restricted The conditions caused, in part, by the Niagaran reef system described above (Dellwig, include 1955; halite, Kunasz, nodules Minerals reported in anhydrite, sylvite, carnallite 1955). 1970), (Nurmi chalcedony and polyhalite Friedman, the (Dellwig, 1977), Salina (Dellwig, 1955), authigenic salts Ca-borate quartz and (Gill, 1979), hematite, pyrite, and both illitic- chloritic shale (Lounsbury, 1963). The Salina A-l salt formation in the basin is the only known potash (Nurmi and Freidman, 1980; Sonnenfeld, 1985). salts is equivocal. Matthews somewhat The geologic 1977; history (1970) bearing Elowski, of and these Matthews and Egleson (1974) thought the A-l salts represent the start of a megacycle of deep-water evaporite deposition in the basin, while Nurmi and Freidman (1977) suggested that the A1 potash salts precipitated in a highly desiccated, marine basin. Figure 2-5 illustrates the shallow geology and stratigraphy of the Salina A-l unit in relationship to the Niagaran reefs and the Salina A-l carbonate. (a mixture cover an of NaCl area of and KC1) 33,700 bearing units km2 , and occur The sylvinite of the A-l in multiple salt beds between lm' and 4m thick that coalesce into a single bed 1520m thick near the northwest area of the basin (Matthews and 88 t h in n e d SYLVITE SYLVITE A* 1 C A R B O N A T E A -1 P O T A S H ZO NE A -1 S A L T , 5C m 2 0 km Figure 2-5. Salina „ . „ ,A_1 salt s t r a t i g r a p h y a n d E g l e s o n ( 1 9 7 7 ). ’ after Matthews 89 Egleson, sylvite 1974) . is In thinned the and northern truncated area by that intersects the A-l carbonate. of an the erosional are apparently encased the surface A notable feature of the A-l salt is the lack of Mg-K-S04 evaporites, layers basin completely observation led Matthews and Egleson as the sylvite in halite. (1974) This to suggest that the Michigan evaporites belong to the class of highly MgS04 deficient deposits categorized by Braitsch (1971). ORDOVICIAN FORMATIONS Hydrocarbon formations and brine production has, until recently, Albion-Pulawski-Scipio (Figure 2-6) . fault zone upwarp now attributed area located has to (Ells, Trenton composed and of (wackestone) minerals and This trend along an Black synclinal wells in the form Hydrocarbon production Formations, dolomite, 1982). are finely locally both open rich to of is of in long This crest, the fault from the which are limestone argillaceous interconnection both samples are termed the Trenton-Black River this study. its crystalline Because of their often 35 mile along the Michigan basin. fracturing River aged along Southern and fossiliferous, and centered in upwarp dolomitization 1967). been is a highly dolomitized, a general (Taylor, because fault from Ordovician zones, (TBR) these brines in NORTH •• Jackson I s • i o ^ • •* , ^ 0 ; / ^ Calhoun ^ J ' V , J t --------- ) - % U - i Branch I J X1 — r 1- - ± _ Lenawee Hillsdale _____I Figure 2-6. Sample l o c a t i o n map. St. P e t e r S a n d s t o n e f r o m (A), a n d the C a s e ( 1 9 4 5 ) s a m p l e f r o m sample (B). 91 The faulting, or reactivation of pre-existing faults in this area apparently created dolomitized the fault zone this fracture dolomites Taylor, thick, occur dolomite, two ferroan dolomite in the upper section basin margins 1982). in the and grades for 1982). fluids generations (Cohee et al., zone, that In addition to other of 1958; approximately of the referred to as cap dolomite, (Taylor, found A exists (Taylor, in the Trenton rocks 1982). dolomite, the related channels Trenton. 15m This is present only near downward into limestone A second generation of regional dolomite is extreme western and southwestern area of the basin, where Trenton rocks are almost completely dolomitized (Taylor, 1982). The fracture related dolomite differs from the cap and regional dolomites, as it is non-ferroan, coarse grained, (1975) and suggested between xenotropic that fracture Silurian and temperature of 80°C. suggested by (Taylor, related Devonian 1982). Shaw dolomitization time, at a occurred minimum fluid This is also the minimum temperature Cercone and Lohmann (1987) for the late diagenetic fluids that affected the Silurian reefs. Gas has recently Ordovician St. formations, from Peter the been produced Sandstone northern area and of from Prairie the the lower du Chien basin. These formations contain generally quartz sandstone and dolomitic sandstones. 92 METHODS Seven brine formations were samples collected southwest Michigan, obtained from from from and were Michigan the St. the supplemented of trends, reefs and in a also collected. from M.D.N.R. (1945, listed locations. balance in Table All errors the from These files, Natural and A-2 and Resources the made than analyses Figure in 2-6 this 5%, from reef (#2020) were with 9 reported shows study although in southern Carbonate supplemented 2-4). less of analyses Sixteen samples northern the were analyses of 5 was collected from a gas well both sample trend one sample of water from Missaukee County in central Michigan. Niagaran with River and from files of various oil In addition, Peter Sandstone Trenton-Black Albion-Scipio Department Geological Survey open files, producing companies. the analyses by Case the sample have charge some of the collected analyses had charge balance errors between +6% and +8%. Comparison with analyses made in the present study shows that samples with poor charge balances differed mainly in Cl. These collected analyses were used only in graphical treatments of the data. l:The sample well is the Dart Edwards 7-36 (T22N, R7w, sec. 36). The drillers log records this well as being finished in the Prairie du Chien Sandstone. Sibley (personal communication) suggests that the producing formation is really the St. Peter Sandstone, or perhaps the Bruegers Sandstone. 93 Brine sampling was preformed in the manner explained in detail in Chapter 1. the well were Samples were collected directly head whenever possible, filtered through Field measurements glass included possible, alkalinity. allowed wool and to separate, Watman temperature, pH, from #1 Eh, and filters. and when The N/S samples were diluted in field to avoid possible problems with salt precipitation, occurrence in Niagara/Salina reef wells. a common At each location, one sample was diluted 50% with 5%HN03 for cation analysis and another analysis. diluted 50% with distilled H 20 for anion Hydrocarbon-brine mixtures would occasionally not separate in the field, and in these cases, combined hydrocarbon-water samples were collected in plastic bottles, sealed, and allowed to separate in the laboratory, before being treated as described above. Because of the hydrocarbon and salinity characteristics, fresh water and other additives are introduced N/S build-up. into to prevent salt and paraffin Every attempt was made to avoid sampling any well injected with occurred. additives, Additional sampling TBR wells. hydrocarbons several wells often since years formation. brine or to sample problems were The Albion-Scipio the has early been 1930's, before injection encountered trend has and re-injected for into with produced the past the TBR The limited number of samples obtained from the Trenton-Black River formation reflects the difficulty in 94 finding production wells sufficiently distant from injection wells to insure representative samples could be collected. The samples and gravimetric were analyzed methods using reported in A.A.S, Chapter titrimetric, 1. Five N/S brines and 3 TBR brines were further analyzed for the stable isotope ratios Isotope of D/H Laboratory, Ontario. and 180/160 University of at the Environmental Waterloo, Waterloo, Results are reported in 6°/oo values normalized to SMOW. Measured activity and isotopic concentration values scale were converted following between Sofer and Gat (1972) . GENERAL RESULTS Well listed information, in Appendix compositions waters, of and also analytical, C. the Table 2-1 and isotopic results are is a summary Niagara/Salina lists the one St. collected in this study. and of average Ordovician Peter Sandstone TBR sample Geometric means are listed because the data were found to be log-normally distributed. The Niagara/Salina brines are highly concentrated with TDS values typically in excess of 400 g/1. The high salinity is best exemplified by the Niagaran brine reported by Case (1945) that has a T.D.S. of 640 g/1 (Table 2-4) . The TBR waters are less concentrated with salinities between 300 and 360 g/1. of Na, Ca, and Mg Figure 2-7 shows the relative precentages (mole percentage) and Ordovician waters used that most of the N/S in this samples, in the Niagara/Salina study, and the St. and demonstrates Peter Sandstone TABLE 2-1 Average composition of Niagara/Salina and Ordovician formation waters, Michigan Basin Component NIAGARASALINA Cl Br Ca Mg Na K Sr Rb Li B Si 210,000 2400 74,000 11,500 31,400 9250 2190 24 60 127 2 550 90 50 25 345,000 4720 26 n h 4n hco3 so4 I TDS mci2 n ORDOVICIAN (TBR onlv). 126,000 1030 22,800 5130 30,000 3680 750 8 38 13 3 80 40 205 11 207,000 1580 11 ORDOVICIAN St. Peter 250,000 3100 90,100 9710 28,200 19,500 3160 58 44 107 20 247 10 - 20 404,000 5367 1 Key: All values as mg/1, except MCl2 (meq/1). HC03 : Alkalinity as HC03 MCI-, = Ca + Mg + Sr - 0.5HC03 - S04 n = number of analyses for major components St. Peter Sandstone sample, #8040 50% □ NORTHERN N /S O SOUTHERN N/S A TRENTON-B.R. O St. PETER 9 CASE SAMPLE % □ Figure 2-7 . o □ □ 3 8? (? *4*. T e r n a r y d i a g r a m s h o w i n g p e r c e n t a g e s of C a - M g - N a ( m o l e p e r c e n t ) in N i a g a r a / S a l i n a and O r d o v i c i a n a g e d f o r m a t i o n s in the M i c h i g a n b a s i n . 97 sample are Ca-Cl brine, while the TBR brines are Na-Cl. N/S samples are separated by reef trend and as can contain a be seen, higher the relative southern reef samples. southern reef samples elements, discussed below. in these waters, components Case and (1945) however, in samples percentage Differences are some also of appear Ca to then between observed south), be do the northern and in the other Chloride is the dominant anion while samples these northern (north vs. The S04 and samples alkalinity are below are minor detection. The show anomously high alkalinity values, may be related to dissolved organic acids (Case, 1945; Willey et al.,1975). NIAGARA/SALINA FORMATION RESULTS Previous work (Chapter 1) has shown that the Michigan basin brines may have evolved from evapo-concentrated water and in following samples Figure are 2-8 that compared (d-f). observation, with The the evapo-concentrated into seawater seawater concentration trend shown are from data in McCaffrey et al. (1978). Niagara/Salina in lines (1988) and Carpenter The data shown in the graphical plots are separated northern reef trend and southern reef trend samples with the mid-basin samples (sample #2020, and the Case, 1945 analysis) combined generally good with agreement brines and seawater the is precipitation, evident (Figure 2-8a). trend samples plot on the MgSQ4 southern while trend between samples. Cl-Br in the Several of the northern seawater line past the several A samples start having of lower 98 Figure 2-8. Niagara/Salina formation waters (log mg/1) compared with evapo-concentrating seawater ( d a s h e d l i n e s , d a t a f r o m M c C a f f r e y e t al. 1 9 8 8 ; a n d C a r p e n t e r , 1 9 7 8 ) . A: L o g C l - l o g B r , B: L o g N a - B r , C: L o g K - B r , D: L o g C a - B r , E: L o g M g - B r , F: L o g S r - B r . 99 NIAG ARA/S ALINA 6 5.5) O O. 5 o J -1.5 3.5 B a Z -1.5 5 • 4 .5 o> o 3 .5 5 .5 5 o O CT 4 .5 O 3 c 45 2 0 O» 4 S5 * O £ 3 .5 P A CO o > o _l 1.5 2 2 .5 3 3 .3 Log Br ( m g / l ) Figure 2 -8 100 amounts of Br plot below the seawater line. sample plots above the seawater trend The Case (194 5) line and has a Br concentration similar to seawater concentrated to the K-salt facies. The log Na-Br plot also demonstrates the close agreement with seawater and a division between northern and southern reef trend southern reef samples, plot a as However, cluster samples and very (Figure some near of the 2-8b). the Most northern seawater of the samples, trend line. several northern samples are depleted in Na or Br, and plot as outliers from this cluster. This figure also demonstrates how the N/S brines plot as clusters on the loglog plots rather characteristic of the than as other distinct linear formation waters trends in the basin (Chapter 1). Figure 2-8 (d-f) shows that Ca, Mg, and Sr co-vary directly with Br, with Ca and Sr being highly enriched and Mg depleted from expected seawater values, similar to those (Chapter 1). and Sr-Br found in the characteristics Devonian formation brines A near 1:1 relationship exists between Ca-Br in formation waters most samples, (Chapter 1). similar to other Michigan However, Mg values generally plot more as a cluster below the seawater line rather than in a linear trend. Potassium plots in two group, generally the southern reef samples, K and plot below the seawater trend line. groups, one are depleted in The second group, 101 generally the northern samples and the Case (1945) sample, plot very near the seawater trend line. An important concentrated relationship seawater MCl2=Ca+Mg+Sr-HC03-S04 used brine in is (in meq/1, examining MC12 , defined Carpenter, remains of approximately affected by seawater, l. the precipitation-dissolution, MC 1 2 and during MC12 (meq/1)/Br(mg/1) MC12 is conservative dolomitization, as: 1978). represents the divalent cations balanced by Cl, evapo-concentration evapo- CaC03 , CaS04 , and is not and and sulfate reduction. halite When the log MCI2 values are plotted versus log Br (Figure 2-9), the N/S are brine appear to be either enriched depleted in Br from concentrated seawater. in MC12 or This is also the case for the TBR samples and the Devonian formation water in the basin Cl (Chapter 1). (Figure seawater 2-9b), the N/S brine apparently agree with concentration (Figure 2-8a). — MCI 2 may waters, When log MC12 is plotted versus log appear line, similar to the Br-Cl the plot Chapter 1 discusses some of the reasons why to be enriched or Br depleted in these but the agreement with seawater in both the MC12-C1 and Br-Cl plots suggests that MC12 values are enriched in these waters. ORDOVICIAN FORMATION RESULTS The seawater the Ordovician in Figure seawater Cl-Br (Figure 2-10a). formation 2- 1 0 (a-f). line and A similar samples are compared with The TBR samples plot below extend down relationship is toward seawater found when the 102 Log MCI2 (meq/1) 4.5 4 3.5 3 2.5 1.5 2 2.5 3 3.5 Lo g Br ( m g / l ) 4 4.5 Log Cl(mg/I) 6 5.5 □ NORTHERN N / S O SOUTHERN N / S 5 A T R E N T O N -B . R . 4.5 • St. PETER O CASE SAMPLE 4 2 Figure 2-9. 2.5 3 3.5 4 Log MCI2 (meq/1) 4.5 L o g M C I 2 (meq/1) vs. l og b r (mg/l) a n d log M C I 2 (meq/1) vs. log Cl (mg/l) in t h e N i a g a r a / S a l i n a and O r d o v i c i a n form ati on waters, compared w i t h evapo-concentrated seawater (dased line, data from McCaffrey et a l . , 1988; and Carpenter, 1978) 103 Figure 2-10. Trenton-Black River and St. P et e r Sandstone formation w a t e r (log mg / l) c o m p a r e d w i t h e v a p o c o n c e n t r a t i n g s e a w a t e r ( d a s h e d l i n es , d a t a f ro m M c C a f f r e y et al . 1988 ; and C a r p e n t e r , 1978 ). A: Log C l - l o g Br, B: Log N a - B r, C: Log K -B r , D: Log C a - B r , E: Log M g - B r , F: Log Sr-Br. 104 ORDOVICIAN 4.5 5.5 D «>3 5 5.5 4.5 • TRENTON O S t. PETER 3 2 1.5 3.5 L o g B r (mg/l) Fig u r e V 2-10. 4 105 other cations are plotted versus Br, and in the MCL2-C1 plot (Figure 2-9b) . this study Peter to plot brine samples, The TBR does but are the only samples consistently not rather plot it in this with the resembles collected manner. The Trenton-Black many of the in St. River N/S brine samples by closely resembling seawater at high Br content. ISOTOPIC RESULTS As a part of this study, the stable isotopic ratios 180 / 160 and D/H in 7 Niagara/Salina samples and 5 Ordovician formation samples were measured. The results are listed in Appendix C, and are plotted on Figure 2-11. the global-meteoric water line (GMWL) the best fit line for all and to the right of from Craig (1961), and Michigan basin from this study (Chapter 1). Also shown is formation waters The N/S brine data plot below the meteoric water line, with most samples plotting towards the enriched (positive 8 18o values) end of the Michigan basin best-fit line, from the (Richfield lower Devonian formations River formations, Chapter 1). and the St. Peter intermediate and Detroit The Trenton-Black River water sample (#8040) between similar to water the best plot fit in line a tight and cluster the global meteoric water line. GEOCHEMICAL EVOLUTION OF NIAGARA/SALINA BRINES The lines, Cl/Br agree suggesting well with that originated from previously, the N/S the the Niagara/Salina evapo-concentrated samples seawater concentration formation seawater. appear to plot as As brine noted clusters on 106 50 (MOWS)aeiap MICH. BASIN LINE -50 AMMW • NIAGARA/SALINA O T R E N T O N - B L A C K R.' O S t . PETER 100 -10 0 del 1 8 0 (S M O W ) Figure 2-11. del D /oo S M O W ( a c t i v i t y s c a l e ) vs. del 0 °/oo SMOW in the Niagara/Salina and Ordovician formation waters, M i c h i g a n basin. Also shown is the g l o b a l meteoric water l i n e ( G M W L ) f r o m C r a i g ( 1 9 6 9 ) , a n d the b e s t - f i t l i n e to all M i c h i g a n b as i n f o r m a t i o n w a t e r s c o l l e c t e d in this s t u d y . 107 log concentration plots, perhaps suggesting that formation contains water with a more homogeneous than observed in the However, differences northern reef suggesting and that distribution Devonian in of chemistry southern the formations reef are sampling chemistry (Chapter observed Niagara/Salina homogeneity reflects locations for this between samples, the the 1). limited N/S water compared with the wide distribution for the Devonian. Although the Cl/Br suggest an evaporative seawater origin, differences exist between Ca, Mg, Sr, K and MC12 in the samples when compared with seawater. reflect the geochemical evolution of These differences the water resulting from water-rock reactions or mixing. Ca-Mq-Sr Dolomitization appears to be one of the more important reactions in the evolution of Michigan brine, as it explains the Ca and Mg in these enriched in Ca concentrated The N/S brine is highly (8d), while Mg is depleted from equivalently seawater dolomitization demonstrate waters. (Figure presented that the in 2-8e). Chapter deficiency in The 1 Mg can from model be used for to concentrated seawater can explain most of the measured Ca, based on a 1 to 1 mole replacement during dolomitization. The ca concentrations predicted by this model are compared with the measured values for the most in Figure part, agree 2-12. with The predicted the measured Ca Ca values, supporting that dolomitization by seawater explains the Ca and Mg in 5.5 t 1 "i— i 1 " i■ i r -■-?— |— -t ~~T " I r B W □ o g 4.5 o <0 O 4 W □ MEASURED O PREDICTED ■ 2.5 3 3.5 Log Br (mg/l) Figure 2 - 1 2 . R e s u l t of d o l o m i t i z a t i o r m o d e l ( l o g C a v s . l o g B r , m g / l ) for N i a g a r a / S a l i n a f o r m a t i o n w a t e r s . S qu ar e s ymbols are m e a s u r e d Ca values, c ir c l e s are predicted C a . 108 o "* 3 5 109 this water. For the Case (1945) few lesser concentrated brines, predicted values. A similar Michigan formation water analysis as well as for a an excess of Ca exists over excess is observed in other (Chapter 1), and is interpreted to show that non-stoichiometric replacement of Mg for Ca during dolomitization has occurred, Mg must be considered. or that other sources of Ca or Other Ca sources might include a Ca enriched parent seawater or the addition of Mg by exchange or clay diagenesis. Strontium is highly enriched in N/S brines over what is expected for evaporating seawater plot in a cluster very near (Figure 2-8f), and values the 1:1 line. Sass and Starinsky (1979) suggested that the dissolved Sr/Ca might be used to that indicate the type of carbonate mineral supply 0.009 to Sr 0.022, Starinsky (1979) to brines. which The according Sr/Ca to or reaction (molar) range the model of Sass from and suggested that dolomitization of aragonite and solution-reprecipitation of calcite have supplied Sr to these waters. Thermodynamic calculations also support that the waters are in halite, equilibrium and saturation in some indices calculated only with dolomite, cases, (log along sylvite. IAP/Ksp) for indices were computed using the PHRQPITZ uses anhydrite, Histograms these of minerals, for the N/S samples collected and analyzed in this study, are shown in Figure 2-13. which with Pitzer's equations for Mineral saturation computer routine, activity coefficients DOLOMITE HALITE 30 25 30 20 3 20 10 5 tn 1 -0. B -0.2 0. 2 0 -3 0.6 2 0 LOG 1AP/KSP 2 LOG 1AP/KSP ANHYDRITE SYLVITE 2D • u 15 • c 01 D t r 01 £10 ■ 5 fl rilTh 0 -3-2-1 0 rn_p 1 LOG 1AP/KSP Figure 2-13. 2 3 -A 3 -2 0 LOG 1AP/KSP H i s t o g r a m s of s a t u r a t i o n i n d i c e s ( l o g I A P / K s p ) f o r the N i a g a r a / S a l i n a w a t e r s a n d T r e n t o n - B l a c k River samples . Ill (Plummer et al., were on based thereafter makes no 1989). 10°C (Chapter at 1; adjustment alkalinity data were Estimated 30m, and formation a gradient Vugranovich, for 1986). pressure. first used temperatures The of 23°C/km The program measured in the modeling, pH- and then the modeling was repeated assuming that calcite equilibrium controls pH and alkalinity. A similar range of saturation indices are calculated under both conditions, although average dolomite saturation indice is reduced slightly, the from 0.49 to 0.06, when calcite saturation is assumed. Potassium Potassium values plot below the seawater concentration trend line for many of the samples (Figure 2-8c) , which similar to how many of the other Michigan basin waters plot (Chapter 1). the N/S brines however, is formation The K depletion is less severe in and does not occur in all samples. The depletion of K from formation water is often interpreted to represent illitization of clay minerals upon deep burial. However, depletion seawater brine. may For start example, early in Figure the 2-14 history shows the of a K-Br concentrations in a seawater sabkha brine from Laguna Madre, Texas (Long and Gudramovics, 3.983) . This water was collected from the upper few meters of the sabkha sediments, and exhibits a depletion of K from seawater values, the result of reactions with clay minerals. perhaps This data illustrates that the chemistry of a seawater brine may start to evolve soon after entering sediments, and that seawater t 5 i n r 4.5 *«■* \ 05 4 E Z 3 -5 , 5 112 05 o -j 2.5 SEAWATER 2 1.5 !_____ 2 !_________ I_________ I 2.5 3 3.5 4 Log Br (mg/l) Figure 2-14. L o g K v s. l o g Br ( m g / l ) in s e a w a t e r b r i n e s from Laguna Madre, Texas (Long and G u d r a m o v i c s , 1983) 113 in natural settings may quickly deviate from the evapo- concentrated seawater chemistry measured in salt pans. The depletion of K from the Niagara/Salina brine might be due to illitization and authigenic feldspar diagenesis. The Niagaran rocks and the Salina salts contain illite and chlorite in shale partings and as thin, black shale in 1963; the Nurmi lower and Salina Friedman, observed in the rocks (Lounsbury, 1977). Authigenic Trenton Nowak, feldspar formations, layers 1978; has (Sibley, been personal communication), and may be present in the Niagaran rocks as well. MASS BALANCE MODEL The extent to which these mineralogical explain the brine balance model reactions chemistry can be evaluated using (Collins, 1975; Carpenter, 1978). can a mass The model starts with seawater and attempts to derive the composition of average sample N/S (Table degrees (based brine 2-6a) on and from Br) a southern seawater by removal by reduction (or resulting from CaC03 Although will it calculated used, CaS04 dolomitization), precipitation. be by is for an actual the (#2098) to equal dolomitization, aluminosilicate diagenesis, precipitation equally, trend concentrated considering recrystallization of aragonite, Ca reef resulting mineral and from precipitation halite "average" important that sample. Sample dissolution- brine an sulfate composition evolution #2098 was be chosen 114 because its Br content is similar to the average N/S composition. Many type, assumptions the most for might halite Carpenter, being that seawater 1987) include clay a account. by model this the only exchange, recrystallization and the the interaction analytical error Other organic (Stoessell of saturated brine (Wilson and Long, 1984). such is of and that Br acts conservatively. Br breakdown, into mass balance models important source of bromide, sources go and halite with To correctly apply must be taken into The two analyses were corrected for charge balance distributing the error proportionally among components relative to their concentrations (corrected compositions are also listed in Table 2-2). initial seawater composition solution of the brines. this al. example Finally, it is assumed that the represents the actual parent The seawater compositions used are taken directly from data in McCaffrey in et (1988). The mass balance results (Table 2-2) show that each liter of average N/S brine might have evolved from seawater by the formation of 192g of dolomite, the recrystallization or dolomitization of 213g of aragonite (containing 10,OOOppm S r ) , and the formation of 56g of illite. followed either of two evolutions. the precipitation 35,840mg of Cl. of 59g of halite Alternatively, Na and Cl may have In order to explain Na, is required, the dissolution removing of 51g of halite can be used to explain Cl, but in this case, 43,300mg 115 TABLE 2-2 EVOLUTION OF NIAQARA/BALINA BRINE Ll Component Br Cl Ca Mg Na K Sr Average N/S brine 2400 210,000 74,000 11,500 31,400 92,500 2190 50 90 4720 so 4 HCO 3 mci2 Average corrected 2420 215,900 72,000 11,200 30,560 9000 2130 50 90 4562 #2098 2560 230,000 79,600 16,700 40,200 8780 2300 35 350 5393 #2098 corrected 2650 247,800 77,200 16,200 39,000 8500 2230 35 350 5233 Corrected: corrected for charge imbalance, all values in mg/l, except MCI2 (meq/1). lb. Evolution of average Niagara/Salina brine (values in mg/l) ______________ Ca______Mg______Sr Seawater (Br=2440) Dolomitization (192g) 48,200 14,500 53,800 185,000 2820 1.1 5500 Halite (59g) -64,350 -23,240 36,000 62,900 11,200 2130 Average... brine 72,000 11,200 2130 Excess a) 36,200 9120 b) 64,400 2130 (**)C03 -26,870 precipitation resulting from S04 reduction Predicted Brine a).. b).. MC12/ 61,010 -37,000 Recrystal-970 ization of Aragonite (*)Illite diagenesis (56g) K_______Na________ Cl_____ S04 9000 30,560 -35,840 149,200 50 1.1 1.7 9000 30,560 215,960 66,800 66,800 50 1.9 116 TABLE 2-2 (Cont'd.) Ci. Evolution of Sample #2098 (values in mg/l) ________ : ______ Ca________ Mg____£r_____K________ Ha______ Cl Seawater (Br=2630) 52,600 15,500 46,900 185,500 SQ4 MC12/Br 70,300 1.0 Dolomitization 60,025 -36,400 (189g) Recrystal-1020 ization of aragonite (*)Illite diagenesis (71g) 2230 3590 7000 (**)C03 -29,340 precipitation resulting from S04 reduction -70,300 Halite -7900 -12,200 (20g)______________________________________________________________________ _ Predicted brine a) b)..... 33,300 62,600 16,200 2230 8500 39,000 173,300 35 1.2 1.8 Measured brine 77,200 16,200 2230 8500 39,000 247,800 35 2.0 Excess a).... b ) .... 43,900 14,600 74,500 74,500 Key: Seawater: Composition of seawater based on measured Br. Predicted brine is sum of reactions. MC12/Br: MC1 2 (meq/l)/Br (mg/l), where MCl2=Ca+Mg+Sr-S04-0.5HC03 (*) : The aluminosilicate reaction used is: 2K^ + 3Al2 Si 20 5 (0H)4 + CaC03 = Ca + 2KA121AlSi3 )0j0 (OH) 2 + C02 + 4H2<3 (**) : Amount of Ca removed by CaC03 precipitation resulting from S04 reduction. Predicted Ca values: a): concentration when resulting from S04 b ) : concentration when resulting from S0 4 Ca is removed by CaC03 precipitation reduction. Ca is not removed by CaC0 3 precipitation reduction. Excess: measured amount minus predicted amount for case a and b. 117 (1.88m) the of Na must be removed from solution to account for measured Na. This later evolutionary scheme is not listed in Table 2-2, for reasons discussed below. A similar evolution dolcmitization of 223g of aragonite, The Na precipitation of calculated 189g of carbonate and which is about 1.5 sample. is for rocks, the formation of sample #2098, recrystallizing 71.3g of illite, times the amount required by the average chemistry 20g might of be halite, explained or by the alternatively, if dissolution of 103g of halite is used on to balance Cl, then 48,300mg of Na must be removed to account for the measured Na (this not listed in Table 2-2). These reactions appear to account for most components in the brine, however, a large excess of Ca and Cl need to be explained, and role the of halite dissolution must be established. a Ca excess predictions of during sulfate reduction, or by (0.9m/l) Ca over the model is removed with S04 (either CH20 + S04= + Ca2+ = CaS04 mineralization during precipitation 66,800mg/l (1.88m/l), moles/1 excess is not in Ca. accounted concentrated illitization, (to balance for in the removal, + is in balancing excess the by 0.9 a significant amount of CaCl2 seawater has been sulfate M g 2+ In the evolution by Na) , Cl approximately Thus, CaC03+ H 2S ; dolomitization, 2CaC03 + S042- = CaMg(C03 )2 + CaS04 ) . halite versus The average N/S sample has 36,000mg/l (line a) , when precipitation evolution involved scheme where in dolomitization, and halite precipitation 118 A decrease explain in some the of amount the of extra Ca Ca, removed but not by sulfate the extra might Cl. A possible source discussed below may be the input of a CaCl2 rich brine, which would have caused the halite precipitation to occur (Holser, 1979; Braitsch, 1971). The possibility remains that Cl should be balanced in the model by halite dissolution, with removal of the added Na by exchange composition, onto exchange dissolution could the predicted predicted Ca 72,OOOmg/1. halite clays add Ca for Ca. of Na For the generated 37,800mg of Ca, (line a; from which when 36,OOOmg/1), very near the average Thus, it would appear dissolution average accompanied that added to in composition an cation evolution a of by exchange could This evolution however, would require the dissolution of a large amount of halite, 5lg/l explain the brine evolution. by halite results brine brine of halite for the average brine and 100g/l for sample #2098. Dissolution of halite is unlikely because: (1) a seawater brine saturated with halite was used as the parent solution, and would not be able to dissolve halite, Na/Br ratios do not affected the brines, support that formation and support and meteoric halite dissolution has (3) the stable isotope data do not water dissolved that (2) the Cl/Br and or salt. seawater The has evolution entered calling the on halite dissolution is therefor dismissed and the by dolomitization, S04 removal by either reduction or CaS04 precipitation, aluminosilicate reactions, and evolution halite 119 precipitation associated with an input of CaCl2 is suggested. ENRICHMENT IN CaClg Although evapo-concentration of seawater may explain the origin of these brines, the enrichment in CaCl2 suggests that a more complex evolution must be considered. This enrichment in CaCl2 also represents the enrichment in MC12 observed in Figure 2-9. The N/S samples, on average, have a MC12 (meq/l)/Br(mg/l) of about 2 with values 2.7, expected ratio far seawater MC12 from the (Carpenter, 197 8). (as CaCl2 ) is by the carbonate minerals; CaCl2 (aq) + 1978). of 1 ranging up in One mechanism evaporating for increasing reaction of aluminosilicate 2KC1(aq) + CaC03 + 2KA12 (AlSi3)01 Q (0H2) + 3Al2Si2C>5 (OH) 4 4H20 + C02 to and = (Carpenter, Similar reactions can be written using Na-feldspars. The maximum CaCl2 enrichment obtainable from these reactions occurs when all K+ in eguivalent amount of Ca maximum value removed from of 1.2. the 24* seawater is replaced with an , and would increase MCl2/Br to a Potassium Michigan brine, has not been so the upper completely limit of MCl2/Br=l.2 helps illustrate the extreme enrichment of MC12 in these waters. Exchange of Na for Ca on clay minerals, non-stoichiometric dolomitization, replacement of considered are for Mg during and lack of complete removal of Ca as CaS04 minerals are possible explanations balanced by Cl. Ca for some of the extra Ca Three other sources of CaCl2 that can be the diagenesis or dissolution of MgCl2 120 evaporites, and a pre-existing enrichment in CaCl2 in the seawater parent to the brines. The diagenesis or dissolution of evaporite minerals such as carnallite might generate MgCl2 solutions that would be subsequently altered to CaCl2 by dolomitization. Although previous work has suggested the potash deposits in Michigan are primary salts (Matthews and Egleson, origin may considered be a equivocal. primary Sylvite seawater evaporite "dynamo-polythermal precipitation" Draitsch, 1971; Garrett, 1970; is 1974), the not generally mineral during (Borchert and Muir, Sonnenfeld, 1985), 1964; although some potash deposits are suggested to be primary in origin (Sonnenfeld, 1985). Recent thermodynamic modeling by Harvie and Weare (1980) supports that sylvite is not primary during normal seawater evaporation conditions, and fractional crystallization both in equilibrium evaporation schemes schemes do not consider carbonates, however). In short, the "physical chemistry of evaporating seawater does not sylvinite (KC1 plus NaCl) normal circumstances" Sylvite can 6H20, or undersaturated may go before through (Garrett, 1970). also form by the thermal the seawater (Garrett, 1970). of reactions cycles as breakdown of KMgCl3 *6H20 = KCl^s j + MgCl2 through stabilizing favor being directly precipitated under carnallite during burial: + (both leaching these sylvite of carnallite Potash deposits during (Sonnenfeld, by burial personal communication) , which liberate large amounts of MgCl2 brine 121 and heat (Garrett, 1970). These MgCl2 solutions would have been quickly altered to CaCl2 upon reacting with carbonates minerals. Whether the sylvite is a primary or secondary mineral deposit in Michigan geochemical (1974) study suggested is of not clear. these the Br In salts, content the only Matthews of the reported and salts Egleson show the sylvite is primary, but other interpretations of their data are possible. The Br in the sylvite of the one reported core from the mid-basin area in Michigan decreases from 4 340 to 2320 ppm over the top 0.5m of underlying 13m of the potash core, potash averages 2100 ppm. Kuhn (1968) reports for the core. however, In bromide the in the These values are similar to those descendent which are listed in Table 2-3. or secondary sylvite, A more detailed examination of these salts is warranted, but the possibility exists that the sylvite in Michigan may have originated from a carnallite precursor. A second source of MgCl2 fluids would incongruent dissolution of the carnallite. the stratigraphic relationships of the A-l be from Figure 2-5 shows sylvinite in the basin, which is also shown in cross section. northern area of the basin the the sylvinite is salts In the thinned by erosion and is truncation by an erosional surface of the A-l Carbonate. Interaction concentrated seawater and would have of would altered the have any carnallite dissolved remaining with the lesser­ carnallite carnallite to Table 2-3 Bromide concentrations characteristic of potash minerals Genetic Type_______ Description Carnallite Br CPPJIlL Sylvite Br .(ppm). Primary Crystallization from seawater 3000-5000 3000-4000 Descendent Crystallization from second cycle brines 1700-3000 1500-3000 Secondary Alteration at depth 1000-2000 by brines and temperature 1000-2000 Posthumuous Late alteration by groundwater 1000-1700 Not applicable From Kuhn (1968) 123 descendent sylvite (Garrett, 1974; Krauskopf, 1979). Both the dissolution and alteration of carnallite would produce MgCl2-rich brine. In order to estimate the composition of the fluids derived from the alteration or dissolution of carnallite and involved in dolomitization, the composition of a solution in equilibrium dolomite, with and calcite was (Plummer et using a carnallite, a l . 1989) temperature formation temperature. carnallite-halite halite, calculated. was of sylvite, used 50°C, The to make the anhydrite, PHRQPITZ this approximate model calculation, present-day Bromide was estimated based on the mixture being the only source of Br (please see discussion at the end of this paper) , using an initial Br content of 3000 mg/kg in the carnallite, which is within the range for primary carnallite (Kuhn, 1968). PC02 was not controlled in these calculations. The results of this calculation are listed in Table 25, and suggest that this hypothetical bittern produced from potash salts is enriched in Ca, Na and Cl over concentrated seawater, characteristics common to many N/S samples. importantly, the approximately 2.5, many of the N/S Although the MC12 calculated which has and is the Case variable concentration chosen for the carnallite, support that mechanism. a MCL2/Br is also similar to the values samples value bittern More enrichment of CaCl2 (194 5) based on of in sample. the Br these calculations (MC12 ) can occur by this TABLE 2-4 Modeled brine derived from potash salt compared with N/S brine and seawater Component Modeled Case-1 Case-2 pH aH20 TEMP °C 6.18 0.49 50 3.55 3.55 65a 65a Ca Mg Na K Cl so4 ALK Br mc12 TDS MCl2/Br 158,800 20,470 9400 44260 395,000 5 36.8 3830° 9607 631,522 2.7 253,000 8830 26 26,200 494,600 212,600 10,100 4878 21,800 432,900 nil * 2000° 4068 9550 579328 2.3 nil 1482 4290 10867 642798 2.5 Vi Seawater nil 84,200 17,100 21,900 208,000 103,000 nil 4180 4782 438,000 1.14 Key: All values as mg/kg, except MC12 (meq/kg). Modeled brine is a solution saturated with sylvite, carnallite, halite, anhydrite, dolomite, and calcite. Case samples are from the Niagara/Salina formation, from the Gulf Salina-1 well, sec. 34, T. 15N, R. 4E.,Michigan, permit # 10551. Case-1 sample was collected from a drill stem test, and the Case-2 sample was collected at the surface from the flowing well. From Case (1945). a: Estimated temperature based on depth, b: Reported to include organic acids, c: Estimated, see appendix. This example is intended only to point out that the enrichment in MC12 (as CaCl2 ) may be the result of reactions involving potash salts, that the Niagara/Salina from these salts. based although on formation water originated solely This is most likely not the case because present-day insufficient it is tempting to suggest volumes sylvinite of brine volumes would be (Chapter generated. 1) , The Salina A-l salt contains between 510 and 720 km3 of sylvite (depending on %KC1 chosen), representing an average of 2790 km3 of primary carnallite. The isothermal breakdown of lm3 of carnallite produces 0.22m3 of sylvite, 622 and approximately liters of water (Borchert and Muir, 1964), therefore, 1C , some 1.7x10 liters of water may have been liberated from the present-day A-l sylvite. This volume represents less than 25% of the total pore volume in the underlying Niagaran formation assuming rocks a formation similar porosity brine, originated (estimated from of such chemistries 10%) . as Salina and volume the of If St. seawater the Peter (as salinities), volumes of solution are required. 7.9xl04 deep km3 Ordovician formation suggested then and by even brine, their larger While it does not appear realistic that the Niagara/Salina brine originated only from the breakdown of carnallite, they may have been supplemented by this process. A third source of CaCl2 (MC12 ) could be enrichment of the parent seawater of the brines, concentration. explain Enrichment before evapo-concentration might for example, between MCl2-Br criteria, occurring before evapo- in the strong Figure parallel relationship 2-9. It is not clear what if any, in brine chemistry can be used to test the hypothesis that the brines originated from a CaCl2 enriched parent might seawater. be potash However, consistent salts with proposed an "anomalous” parent the by model of Matthews the and seawater Silurian Egleson A-l (1974). Anomalous is used here to signify a difference in chemistry from the is used taken seawater measured in this from Matthews study McCaffrey deficient in MgS04 for the et and Egleson in evaporative salt pans, al. reference (1988) and (1974) suggested because of seawater the lack associated with the A-l potash unit. and Carpenter that which (1978) . seawater of MgS04 In "normal" was was salts seawater evaporation schemes, the evapo-concentration from the halite to KC1 facies results in the deposition of large volumes of MgS04 salts originated (Garrett, from a 1970). "normal" In fact, seawater, then if the potash roughly equal volumes of MgS04 and KCl salts should be found in the basin. The lack layers, salts on either side of the sylvite and the thin or non-existent anhydrite layers which separate Carbonate 1977), of these the A-l salts from the (Matthews and Egleson, suggest that seawater in Niagaran 1974; the Nurmi and and Michigan the A-l Friedman, basin was 127 deficient Egleson, in MgS04 1974). during the Silurian (Matthews and One explanation for the lack of S04 salts is that dolomitization and sulfate reduction occurred near the basin margins, and perhaps outside of the basin margins to deplete MgS04 from the seawater that entered the central Michigan basin during the Silurian. While these reactions would not enrich the seawater in absolute amounts of CaCl2 , other water-rock aluminosilicates, reactions, may have increased evapo-concentration occurred. "anomalous" salts those MC12 involving values before If the seawater chemistry was and produced primary sylvite without the MgS04 (carnallite) earlier, perhaps then it and may the have MgCl2 also solutions been enriched described in CaCl2 . However, an "anomalous" seawater is not required to explain the evaporite example, salts proposed in the a model basin. for the Garrett origin of (1970) for sylvite that calls on the direct precipitation of carnallite from normal seawater, without the associated MgS04 salt. The evolution of the potash salts in Michigan may have been quite complex, but it is precursor, possible or they that may they have evolved evolved from from an a carnallite "anomalous" seawater source. ISOTOPIC EVOLUTION Two general models for the evolution of stable isotopes in sedimentary basin brines have been advanced. al. (1966) basin waters interpreted to the represent stable the isotope Clayton et composition of flushing of meteoric waters 128 through host the basin, formation along with carbonate isotopic minerals. presented by Knauth and Beeunas 1964), is that represents the the dilution meteoric water. however, isotopic This of equilibration An (1986) with alternative and others composition of latter explanation (Degens, basin evapo-concentrated view, brines seawater by is accepted here, it is not possible to correlate isotopic dilution with chemical dilution in these waters. The Niagara/Salina samples do not exhibit either isotopic or chemical evidence of dilution. A conclusion that can be reached is that the N/S waters retain an isotopic composition reflecting evapoconcentrated seawater (Chapter 1). A number interpreting of the factors isotopic need to composition thought to be derived from seawater Beeunas, 1986) . seawater is The isotopic controlled by be considered of formation waters (Chapter 1; Knauth and composition many when of variables, evaporating and as such, seawater may exhibit a wide range of isotopic values during evapo-concentration. This Beeunas reported (1986), inclusions, who Pierre et al. was illustrated values (1984), and by from Knauth halite Holser and fluid (1979), who reported values from sabkhas and lagoon waters concentrated up to halite saturation, and Nadler and Magaritz (1979), who reported evaporation values for Mediterranean seawater pans concentrated past halite saturation. found isotopic that the composition in This later study of seawater after reaching halite saturation is more negative in SD than the 129 seawater source. The Niagara/Salina brine far past the start of halite saturation, have evolved unlike the from a examples seawater cited brine above. is concentrated and therefore, having a may composition Additionally, ancient seawater may have had an isotopic composition different from present seawater. For example, Brand and suggest that Ordovician seawater was about 1ft in ■LO0 than present ocean water. an extent then the seawater shifted towards more negative In sum, the Veizer (1980) -5.5°/oo lighter . If seawater varied to such evaporation path would have S18o, and perhaps £ D values. it is not possible to constrain with any certainty isotopic composition of the parent seawater of the Niagara/Salina brine. It is also difficult to imagine that the basin waters have not reacted during their history with the carbonate and evaporite function minerals of ubiquitous water-rock to ratios, the basin. carbonate Although reactions a would enrich the brines in 180 (Land, 1982; Clayton et a l ., 1966). If isotopic isotopic equilibrium composition of can the be water demonstrated can not then be the entirely primary. The extent of isotopic equilibrium between the brines and carbonate minerals can be evaluated in a general manner. Such an evaluation was attempted by Clayton et a l . (1966) who attempted to demonstrate that Michigan basin waters are in isotopic equilibrium with calcite. al. (1966), however, made assumptions formation Clayton et concerning mineral 130 180 values and formation temperatures and did not consider that dolomite isotopic equilibrium may play a role composition of the water. in altering the Recent data help constrain the temperature and mineral isotopic compositions in the basin and allow for a more refined re-examination of this question. Determining dolomite is if of isotopic course equilibrium hindered because exists of the with lack of knowledge on oxygen fractionation during the low temperature diagenesis of dolomite (1980) discusses describe (Land, four 1980? Carpenter, equations dolomite-water (Table oxygen 1980). 2-3) isotope Land thought to fractionation developed by Northrop and Clayton (1966), O'Neil and Epstein (1966), Shepard (1970). The following average fractionation factor equation can calculated be and Schwarcz from (1970), these four and Fritz and equations: Smith 103 In ALPHA=3.14xl06T—2 - 2.00, where ALPHA=(103 + S18Odol)/ ( 103 + 1ft % 0water) . • Another limitation temperatures needed for temperatures derived from color alterations suggest such a fluid two is the knowledge calculation. inclusions Paleo- and paleo-temperatures of conodont may have been important in the evolution of these rocks and waters: present-day + present-day gradients Cercone, fluid 2 3°C, 1984), inclusions representing (Nunn and 80°C, in the et burial al., 1 1984; km deeper Hogarth, 1985; a minimum temperature found late diagenetic dolomites at in from the TABLE 2-5 Isotopic fractionation factors for dolomite-water 10 In ALPHA(dolomite-water) 3.20xl0^T“2 3.34xlO°T“2 3.23xlO^T 2.78 x 106T “2 + 1.50 3.34 3.29 0.11 (Northrop and Clayton, 1966) (O'Neil and Epstein, 1966) (Shepard and Schwarcz, 1970) (Fritz and Smith, 1970) t—1 U> H All equations corrected to be consistent with Friedman and O'Neil (1977), from Land, (1988). Average fractionation factor: 10 In ALPHA(doiomite-water) = 3 *14 x 1°6t 2 “ 2.00 For calcite: 10 In ALPHA (Calcite-water) = 2.78xlO^T 2 - 2.89 (Friedman and O'Neil, 1977) 132 Niagaran reefs (Cercone and Lohmann, 1987) and in the Trenton (Shaw, 1975). The isotopic composition of dolomite and calcite in equilibrium with several of the northern reef water samples was computed using the estimated present-day temperature, and the two paleo-temperatures. rock values are (°/00 P.D.B.) compared of in Figure Niagaran 2-15 and carbonates reported by Cercone and Lohmann and Lucia (1982) for northern The resulting with Salina formation S 180 values A-l formation (1987) and Sears reef rock samples. Similar calculations were made for calcite using the fraction factor from O'Neil and Epstein (1966), Cercone and Lohmann (1987). the average values the four data from The rock value calculated using fractionation from and the mineral factor and fractionation the factor range of equations rock are shown for reference by the bracket lines. As indicated in Figure be 2-15, the brines do not appear to in isotopic equilibrium with any of the reported dolomites at presentday temperatures. Whether equilibrium with calcite is not clear however, in isotopic occurs but some of the samples appear to be equilibrium with bulk rock limestone values the dolomite values reported by Sears and Lucia (1980). With increased temperature, predicted to be in equilibrium with the water increase and approach bulk the measured Niagaran considering dolomite dolomite. that the This values, increase fractionation especially is factor not for the unexpected decreases with I— a— a--- a*--- o— I 80 ° |— o— ■--- o* — ■— oo— J PD. + 2 3 ‘ |— #o- o 80° □ ♦ a o-o P D . + 2 3 * — jPresent Day temp. D>— ®~CD Present Day temp. late dolomite H whole rock |---- 1 I Niagaran |------------ j LJ -15 Figure I 1 1 1__L J I 1 L J ! I -10 -5 0 del ls0 % o (PDB) dolomite I I L I 1 late calcite 133 A l - C 0 3 I— SAMPLE O 2100 B 2097 □ 2092 O 2078 • 2020 Niagaran L _ 1 I 1 1__ 1_I__L. -15 1__1_1__1 ■ 1 1 > 1 I -10 -5 0 del 180 % . (PDB) calcite 2-15. C a l c u l a t e d del 0 ° / o o ( P D B ) v a l u e s f o r d o l o m i t e a n d c a l c i t e in isotopic equilibrium with N i a g a r a / S a 1 in_ formation waters at Eubsurface temperatures of present-day, p r e s e n t - d a y + 2 3 C, and 80 C. Bars show range of values from four different do l o r n i t e - w a t e r f r a c tjigO n a t i o n equations discussed in text. A l s o s h o w n a r e r a n g e s of del 0 values reported in late diagenetic dolomites and calcites, w h o l e r o c k ( W . R . ) , A - l C a r b o n a t e d o l o m i t e s , a n d N i a g a r a n d o l o m i t e s and calcites in M i c h i g a n , from Cercone and Lohmann (1987) and Sears and Lucia (1982). 134 increasing temperature. values in using independently suggest N/S that However, carbonates are similar determined equilibrium temperatures has the with affected the fact to that those measured calculated paleo-temperatures dolomite isotopic at might higher composition paleoof the brines. Because of the uncertainty in fractionation factors for dolomites and temperatures, the implications calculations are somewhat tenuous. of Clearly more research is needed to test whether isotopic equilibrium exists the brine and host rock minerals and cements. can be established, evapo-concentrated refined. suggest The then seawater results that the of carbonate simple by model dilution water calculations equilibrium at between If equilibrium of meteoric these these must do of be however, warmer paleo- temperatures may have affected the isotopic composition of the brine, and that re-equilibration may not have altered the water equilibration (1986) is not model, composition of and $180 values. considered further during basin Water-mineral in the Knauth suggests formation waters may cooling that and the be decoupled Beeunas isotopic from the chemical evolution (Chapter 1). MODEL FOR THE ORIGIN AND EVOLUTION OF NIAGARA/SALINA FORMATION BRINES The linked, origin of Michigan basin Ca-Cl brine has been in the past, to geochemical processes such as shale membrane filtration (Graf et al., 1966). The data presented 135 here suggest originated that from the Niagara/Salina evapo-concentrated formation seawater. water The brine appear to have been derived from seawater concentrated past halite saturation, the Na content thus halite saturation of the brine. far has lowered Dolomitization has likewise removed Mg from the parent seawater and replaced it with Ca. Additional reactions involving aluminosilicates and perhaps reactions with evaporitic salts has added CaCl2 , and either S04 reduction Dolomitization processes seawater that brine or CaS04 and mineralization halite precipitation transformed into the the Ca-Na-Cl have removed appear original brine now to be S04 the Na-Mg-Cl-S04 found in the basin. The high Br levels in the N/S samples suggest that the parent seawater was concentrated The origin of the brines may, Salina A-l salts, the minerals in the basin. only to K-salt therefore, formation be precipitation. linked to the containing potash During deposition of the A-l salts, dense seawater bitterns may have entered the Niagaran rocks along the reef margins and may have moved downward through the accumulating halite into the underlying Niagara rocks. During later Salina salt deposition, seawater derived brines may have infiltrated the Niagaran rocks, however it would seem unlikely that brines generated during younger periods of evaporation could accumulation of halite. reflux through the thickening Later compaction of the salts may 136 have been very important in forcing brine into the adjacent formations. As samples For previously discussed, agree well example, very many from expected some with northern of the northern evapo-concentrated samples seawater values, a are not seawater. depleted characteristic many of the southern reef samples. reef in common K to This may indicate that the northern waters were derived in part directly from the salt during the its spatial locations, Figure This relationship the 2-5 compaction. A-l potash shows where observation may between salts, the N/S the and northern the waters reflect A-l were reef Carbonate. sampled in relation to the different salt facies in the Salina A-l salt and the vertical salts. The Carbonate in relationship sylvite close is between thinned proximity and to the the different intersects northern the A-l ree f s , while the underlying halite thins below the potash salts area. A-l in this Fluids derived from the A-l salts during compaction, would have had an easy pathway for migration either through the A-l Niagaran Carbonate, or carbonates. alternatively, The short downward migration would into the minimize water-rock interactions, explaining for example, the lack of K depletion. located near depleted in K, In the contrast, A-l salts the southern and contain suggestive of water-rock reefs water are not generally interactions. Any fluids squeezed from the potash salts would have had ample 137 opportunity to react with formation minerals before entering the southern reefs. ORIGIN OF TRENTON-BLACK RIVER BRINE The Trenton-Black River formation samples show chemical evidence of mixing between evapo-concentrated seawater and a more dilute water, possibly seawater or freshwater. Whether this mixing represents dilution of a pre-existing brine by dilute water, or enrichment brine is not clear. of dilute (salinity) by migrating Figure 2-16 shows the Br values in TBR waters from the Albion-Scipio area. Br water argues against from production operations. The smooth variation in localized dilution resulting This distribution does not rule out that regional infiltration of dilute water has occurred in this area of the basin. Alternatively, the fact that the deeper Ordovician formation sample (St. Peter Sandstone, #8040) is more saline suggests that an up-dip migration of brine from the deep basin may have also occurred. If the explained, Three history the TBR brines is to be fully then the end member waters must be constrained. saline geology of of end the members area; are seawater possible considering the (perhaps Ordovician), the present-day Niagara/Salina formation water, and the presentday Devonian formation water. Extrapolation of the data back to the seawater trend line (Figure 2-10a) that start the saline of halite precipitation. end member precipitation was and concentrated the start Cl-Br suggests between the of MgS04-salt If the TBR brines originated from Ordovician (400 Figure 2-16. Br ( m g / 1 ) in T r e n t o n - B l a c k R i v e r f r o m the A l b i o n - S c i p i o t r e n d . formation 138 Br ( m g / I ) brines 139 seawater, then they were concentrated to this degree before dilution occurred. However, this seawater composition is also similar to the present upper Devonian formation brine, both in its salinity and suggesting that Devonian down into the possible TBR because in its Na-Ca-Cl chemistry, formation brine may have migrated formations. the Salina Downward salts do migration not cover is the Ordovician formations in the Albion-Scipio area, the AlbionScipio fracture system is known to extend up to the Devonian formations (Carpenter, personal communication), and areas of possible basin recharge have been identified central area Vugranovich, The collected formation of Michigan (Wilson in the south- Long, 1986; and 1986). chemistry of from central the sample, the #8040) Ordovician basin might formation area suggest (the St. brine Peter however, that the previously proposed waters may not be the saline end member water. that This is samples might sample similar (Table have a highly many 2-1). had, alternatively, in is that respects This before Ca-Cl concentrated to suggests dilution, rich a waters the that have brine Niagara/Salina the Ca-Cl Ca-Cl TBR waters chemistry, migrated or into, and mixed with more dilute waters in the Trenton-Black River formations. Therefore, a third hypothesis is that the TBR formation brines are mixtures of Ca-Na-Cl altered to a Na-Ca-Cl composition. brine which have been The feasibility of this 140 hypothesis can be tested using Niagaran/Salina sample #2099, from the member. southern reef thermodynamic a typical N/S brine collected area, was used for the saline end Seawater from Nordstrom et a l . (1979), concentrated to gypsum saturation (and in equilibrium with calcite) used for the dilute end member composition. simply a convenient standard that precipitation needed to remove Ca. several brine/freshwater ratios log plot of Cl-Br Figure 2-17. and dolomite, and with these the and any The symbols. In the end (1., 0.9, the results of second positions and then from this case, (end the CaS04 0.75, 0.5, 0.25, and are shown on a log- member other mineral equilibration different maximizes as mole percentages anhydrite, mixing. without This choice is of Ca-Mg-Na The mixing was done using two scenarios, equilibrating was The results of mixing at .1, 0) are presented in Table 2-6, by modeling. waters with maintaining that case the first calcite, equilibrium shown end members members first supersaturates are plot in in case), and upon as solid were mixed slightly mixing was calculated without maintaining equilibrium with any mineral. These results are shown as open symbols on this diagram. In either case anhydrite was predicted to supersaturate in all mixtures. The results explained by (Figure 2-17) show that brine/seawater mixing at Cl/Br ratios ratios between are 0.2 5 and 0.5, while the relative percentages of Ca-Mg-Na in these brines suggest a brine/seawater ratio near 0.25. This is 141 TABLE 2-6 Modalad mixtures of Niagara/Balina brine and seawater All values mg/kg Brine/ Seawater ratio 0-:l .1: .9 PH aH2o Ionic Strength TEMP 7.33 0.932 2.246 5.15 0.914 2.940 Ca Mg Na K Cl so4 ALK Br 4581 1080 39015 1446 70122 3400 16 244 30 30 .25:75 4.75 0.882 4.025 30 .5: .5 4.35 0.819 5.874 30 .75:.25 4.05 0.748 7.736 30 .9: .1 3.88 0.703 8.851 30 1— :0 3.77 0.672 9.598 30 11136 2580 39605 222 87275 1555 701 550 21590 4742 40490 3376 113000 809 606 1010 39888 7998 41969 5306 155900 338 378 1777 59026 10829 43445 7236 198800 147 219 2544 70845 12343 44332 8394 224500 90 156 3004 78853 13282 44922 9165 241600 65 124 3311 13. 1 5.0 78 .9 21.6 7.8 70.6 31.6 10 .4 58 .0 38 .7 11.7 49.6 42.0 42 .0 12 .0 44.0 12 .2 43.8 Mole percentages %Ca %Mg %Na 6.2 2.4 88.4 Mineral Balance Mineral Phase fmoles/kai Anhydrite -0.066 Dolomite -0.14 6 Calcite 0.292 Key: -0.0759 -.112 0.229 -0.0685 -0.0648 0.134 -0.0480 -0.0005 0.004 -0.0247 0.046 -0.092 -0.010 -0.0001 0. 067 0. 078 -.133 -0.155 Composition of various mixtures of seawater evaporated to gypsum saturation and a Niagara/Salina brine from the southern reef trend. Results listed are for the case when equilibrium is maintained with anhydrite, dolomite, and calcite. * Seawater concentrated to gypsum saturation **: Niagara/Salina brine sample #2099 Mineral balance: += mineral dissolution, - = mineral precipitation 5.5 .25 4.5 Log Cl ( m g / k g ) 142 3.5 1.5 2 2.5 3 3.5 L o g Br ( m g / k g ) 4 O MEASURED A A P R E D IC T E D 50%Mg .25 Ca Na Figure 2-17. Cl-Br (log mg/kg) and relative Ca-Mg-Na composition calculated to result from mixing of N/S sample (12099 (point 1) with seawater concentrated to gypsum saturation (point 0). Numbers indicate seawater/brine mix ratio. 143 is the case regardless reestablished or not. whether Some of mineral this equilibrium difference might is be explained by a lower Ca/Na ratio in the saline end member or a difference water in temperature, (seawater) 56g halite/kg) result of may have or alternatively, dissolved before mixing, Nevertheless, (approximately or had a lower Ca/Na evapo-concentration precipitation. halite that dilute past the start of as the gypsum the results show that mixing of Ca-Na-Cl brine with seawater for the TBR formation waters. is a possible Mixing with explanation seawater would result in CaS04 , dolomite, and calcite saturation (depending on mix ratio), and if these minerals precipitate, Ca removal would follow. reactions reported Geologic have occurred anhydrite is evidence is given the last that by some Miller of these (1988), diagenetic mineral who to precipitate in the Trenton-Black River rocks in the AlbionScipio trend. St. PETER SANDSTONE WATER The one brine sample collected from the Ordovician St. Peter sandstone formation allows only a limited of the water chemistry in the deep basin. collected from a gas producing from a depth well of in This sample was northern over evaluation lower 3000m. Michigan Although the reliability that can be placed on interpretations made from a single brine analysis is limited, this water deserves some attention. saline (404 g/1 TDS) Ca-Na-Cl the unique nature of This water is a highly (Figure 2-7) brine. Inspection of Figure 2-10 demonstrates that this sample has a Cl, Na, seawater trend K and Br chemistry that match evapo-concentrated very line well, although for Cl. Mg it plots above is highly depleted the and seawater Sr greatly enriched over expected seawater values. Application of the dolomitization shows depletion model discussed resulting from stoichiometric explain most the observed Ca. is interpreted seawater that to have evolved earlier dolomitization from highly dolomitization. reported to (Sibley, personal clastic 1) , show samples in the the the formation initial St. authigenic Peter in K northern however, is the Berea for other example from seawater reef trend values. of depleted Indeed, K minerals from strikingly of that has been and brine are not seawater content. sample lack aluminosilicate basin, a depletion from Niagara/Salina from their in can This water is sandstone formation, communication), formations (Chapter Many contain Mg concentrated The depletion is curious and somewhat unexpected. produced from a clastic the Thus, except for K, the water evolved by that the in K chemistry similar chemistry observed in the Niagara/Salina samples the to the (Figure 2- 8) , including the lack of K depletion and 87Sr/86Sr ratios (Chapter 1). This water sample may therefore, be related to the Niagara/Salina water and possibly originated during the deposition into the of the Niagara/Salina underlying Ordovician salts and formation. migrated Until down more 145 samples are recovered and analyzed however, this remains a preliminary interpretation. ISOTOPIC EVOLUTION The isotopic the TBR brine data do not originated support from the CaCl2 suggestion brine that source.The stable isotope values in the TBR samples plot as a cluster intermediate 11). of the best-fit SMOW (Figure 2- This is not where a water that evolved by mixing of a CaCl2 Niagara/Salina end line and the of the seawater. best-fit The type brine, line isotopic plotting would values plot of the at when TBR the enriched mixed brine with plot intermediate between a dilute formation brine (plotting near the GMWL) and SMOW or seawater at gypsum saturation, supporting this hypothesized origin. The TBR samples plot sandstone intermediate of the St. Peter sample also and SMOW, which might be consistent with an evolution of brine migrating up from deeper areas of the basin and mixing with SMOW. But making this interpretation based on the isotopic composition of a single brine sample is tenuous. A relationship between £D values and Br (salinity ) was found in the Devonian formation water of Michigan 1) , but as the following list shows, is observed in the TBR samples: (Chapter no clear relationship 146 SAMPLE — 0°/oo_____Br(mq/1^ delD^ /oo_____del— ^ 6074 -26.40 -1.85 1080 6094 -24.30 -1.99 1160 6095 -26.70 -1.76 1250 The lack of correlation might reflect the small number of analyses available, or that both end member have had a similar isotopic composition. water Why mixing is not represented in D values remains a question that, limited amount of data, does not seem may given the answerable at this time. It may also be possible that the isotopic values have been masked by reactions with carbonate minerals, for 180. and the in equilibrium same method Niagara/Salina waters. values least In order to investigate this, the S 18o of dolomite calcite using at with Ordovician the and the brine was temperatures calculated described for Figure 2-18 compares the calculated ranges dolomites with of S ^ 80 (Taylor, in the 1982). three types Average of isotopic values are -6.8°/oo for the regional dolomites, -7.8°/oo for the cap dolomites, dolomites, and -9.0°/oo respectively (Taylor, values for minerals agree with temperatures. any for the 1982). fracture The calculated in equilibrium with the brines of However, these minerals at related do not present-day the brine values are near those in so°c h&-j PD. +23°C 1— PresentDay ■J R E G I O N A L J • ? ° I I ----- |-------------- F R A C T U R E □ .6094 1 1 O 6095 |---1 C A P I t « I ! I » i i i I L.J L J -15 -10 -5 I I I 0 del ,80 %o(PDB) Figure 2-18. Cal cu la te d del 0 ° / o o ( P D B ) v a l u e s f o r d o l o m i t e in isotopic equilibrium with Trenton-Black River formation w a t e r s a t^ s u b s u r f a c e t e m p e r a t u r e s of p r e s e n t - d a y , p r e s e n t d a y + 2 3 C, a n d 8 0 C. A l s o s h o w n a r e r a n g e s of i s o t o p i c values for fracture, cap, and regional dolomites in the Tre nt on -B la ck River formation, from Taylor (1982). 148 equilibrium with regional present-day+23°C, equivalent present-day geothermal be near isotopic dolomite at represent to equilibrium at burial gradient. temperatures temperature. dolomite temperatures 1km deeper of at the The brine also appear to with near the 80°C, fracture but not related at higher Thus the isotopic compoition of the brine may equilibrium with formation minerals and not the mixing indicated by the chemical data. CONCLUSIONS The following conclusions are made concerning the Niagara/Salina and Trenton-Black River formation brines. 1) The Niagara/Salina formation water originated from evapo-concentrated seawater, concentrated through the halite facies to the MgS04 facies and salt facies. in some cases, into the K- This suggests that their origin is linked to the Salina evaporitic seas in Michigan, deposition of the Salina A-l refluxed into underlying period. Additional salts. Niagaran brine may and perhaps to the Dense brine may formations have been during squeezed have this out of these salts during salt compaction. 2) Dolomitization appears to be the most important reaction to have affected the brine, as it explains the CaMg chemistry. Dolomitization in conjunction with extensive halite precipitation were the mechanisms generating the CaNa-Cl chemistry from illitization or water carbonate while seawater. K-feldspar Reactions diagenesis reactions removed supplied Sr. K such as from the Reactions 149 involving aluminosilicates and/or late stage evaporites have apparently increased the CaCl2 content of the brine from seawater values. 3) Although their origin is similar, the Niagara/Salina waters show differences formation brines which they within the their in the basin, plot Niagara/Salina in on log brine chemistry reflected other in the manner concentration diagrams. may show differences in samples collected formation, from in in The chemistry from different areas of the basin. 4) Black Brine produced River concentrated saline end from Formations seawater member the evolved by more dilute with waters Ordovician are aged mixing Trenton- of water. evapo-concentrated evapoPossible seawater (Ordovician?), Devonian formation brine, or Ca-Cl brine such as found in the Niagara/Salina formations. It is not clear at this time what the true end member waters are. However, thermodynamic modeling suggests that mixing of Ca-Cl brine, such as the Niagara/Salina brine, and seawater can explain the chemistry of the Trenton-Black River water. 5) The isotopic evolution of the formation waters is generally consistent with the model proposed by Knauth and Beeunas questions dilution (1986) for remain. in both evaporating There sets of is seawater, little formation isotopic waters, although many evidence even for though chemical evidence supports it for the Ordovician formation. The isotopic brines composition might reflect the isotopic however, from the chemical isotopic composition equilibrium with temperatures. formation evolution. of the the Niagara/Salina original evolution may evolution. of the formation One brines seawater have has carbonates composition, been suggestion been at formation independent is that affected higher the by paleo- In sum, the isotopic evolution of these deep waters may be independent of the chemical 151 Estimation of Bromide in salt The composition of a water in equilibrium with carnallite, sylvite, halite, anhydrite, dolomite, and calcite was calculated using the PHRQPITZ computer routine (Plummer et al., 1989). This calculation was done for a temperature of 50°C, representative of present-day temperatures in the basin. The pC02 was not fixed in this example. This computation is rather straight-forward using this computer program, however, Br must be estimated. The only source for Br in this hypothetical brine is the carnallite, and any halite that dissolves during carnallite recrystallization. The initial carnallite may have had a Br concentration ranging from 3000ppm to 5000ppm (Kuhn, 1968). A lm3 volume of carnallite (1.67x10 kg) that converts to sylvite (0.22m3) releases 36082 moles of H 20 (649.5kg). If the carnallite has a Br content of 3000ppm, then 5.01xl06mg of Br are released into 649.5kg of water, resulting in a Br concentration of 7713mg/kgs (kgs=kg of solution). This concentration must then be corrected for Br uptake by re-precipitating sylvite and halite. An input of Mg-Ca-KCl into solution decreases the solubility of halite dramatically (Holser, 1979), there-by removing Br from solution in addition to that removed by the sylvite. Br uptake by sylvite and halite was considered in this example, although the amount of Br removed by halite is calculated to be negligible. Using a distribution coefficient of d = 0 .73, (Braitsch, 1971), the reprecipitated sylvite is calculated to contain 5630ppm Br. The total amount of sylvite re­ precipitated is 43 6kg. This removes 2.45xl06mg of Br from solution, leaving a Br concentration in solution of 3930mg/kg. The calculated sylvite has a Br content higher than the maximum reported value in Michigan potash (4340ppm). However, considering the variability in distribution coefficients and that fact that carnallite may dissolve incongruently, the results are encouraging. If a second generation of sylvite precipitates from the remaining bittern (3800ppm Br) , then it is predicted to have a Br content of 2800ppm, near the Br values measured in the Michigan potash by Matthews and Egleson (1974). APPENDIX A APPENDIX A STATISTICAL EVALUATION OF MICHIGAN BASIN BRINES Natural chemical water can makeup. exhibit a types and The wide variation amounts of in its dissolved components will reflect a water's origin and the geochemical processes involved in its evolution. water chemistry Drever (1988), are discussed by reactions, biological operate, chemistry water activity. combining and ion Often to a create reflected by exchange mixing, and number a of doing so, help eguilibria, adsorption, these structure between and processes in the water concentrations Statistical tests can be a useful in elucidating these often complicated in (1981), evapo-concentration, correlations of dissolved components. tool Stumm and Morgan and others, and include mineral dissolution-precipitation, REDOX Processes that control to demonstrate the relationships, processes that control water chemistry. With a goal geochemical evaluation of further characterizing the evolution of the of the brine Michigan chemistry was basin origin and brine, an undertaken univariate and multivariate statistical methods. using Univariate methods are first used to characterize Michigan basin brine chemistry, compare it with seawater, and then average brine composition between formations. means and standard Student's t-test deviations are to compare To do this, calculated, and the is used to test mean compositions between 152 153 formations. The multivariate methods of R and Q-mode factor analysis are then used attempt to find test data statistical controlling the results compared are to brine homogeneity, evidence chemistry. with for The results from and to processes factor analysis previous research which used factor analysis to study saline ground w a t e r s . THIS STUDY The population studied in this Michigan basin formation waters. were collected and analyzed as described population in Chapter was investigation is all Samples of this population for major and minor components 1 subdivided and by Chapter 2. producing The sample formation for statistical testing whenever possible. Statistical evaluations, especially of natural systems, are often based on several underlying assumptions. The principle assumption made in this study is that the samples are random and representative of the parent population, assumption typical of ground water studies. demonstrate the possible short-coming in two Two examples this assumption. The oil wells from which the samples were collected are not random in the basin, but are located conditions favor hydrocarbon entrapment. coincide wi t h , for example, high porosity characteristics representative possible that or unique that might of the waters structural mineralogy, make the formation in are where These areas might features, or associated general. density geologic zones have other water It stratified of is non­ also within 154 formations. traps, Because hydrocarbons reside water produced by with oil non-representative wells. Considering in up-dip areas of density be this, might oil-well samples may not be random or representative of the formation water as a whole. UNIVARIATE STATISTICS DATA DISTRIBUTION Univariate parametric statistical methods are based on a normal samples distribution (Koch and demonstrated normally that of Link, 1971). many distributed the chemical A number geochemical (Ahrens, variables of data 1954; studies sets Koch and in are Link, the have log- 1971, Hitchon et a l ., 1971, Long et a l ., 1986). Before statistical test can be correctly applied therefore, the distribution of the sample population must be determined. (X*) test both the xs used to test raw data and log The chi-squared for population (base 10) normality, using transformed d a t a . The results of this test at the 5% significance level or better (TABLE A-l), distributed, indicate that the except for Na and C l . data are lognormally Histograms (Figure A-l) of Na and Cl show these elements follow a negatively skewed log-normal break distribution, and in slope, populations is not lognormal characteristic (Figure A - 2 ) . clear, but log-probability because distribution, The cause the albeit of two show a overlapping for this distribution Na-Cl skewed, transformed for use statistical tests. plots histograms all data suggest were a log- 155 RESULTS C O MP ON EN T Br Log Cl Log Na Log Ca Log Mg Log X 1550 3.12 1 18000 Cl 5.241 55900 Na 4. 706 43900 Ca 4.555 7610 Mg 3.835 K 4860 Log K 3.472 Sr 1480 Log Sr 3.067 Rb 13.0 Log Rb 0.85 Cs 2.5 Log C b 0.17 Li 39.6 Log Li 1.51 B 92. Log B 1.67 NH4N 266. Log NH4 2.26 HCO 80.5 Log H C O .. 1.60 50 157 . Log SO^ 1.72 17.2 Log I 1.12 51 3.2 Log Si 0.42 TDS 294000 Log TDS 5.452 Br TA B LE A-l OF C H I - S Q U A R E D TEST SD DF SIGNIFICANCE _________ LEVEL 865 0.262 39025 0.135 21400 50.5 20.7 12.9 33.9 0 .2 10 26900 0.298 3500 0.210 5250 0.443 1010 0.321 16.4 0.50 2.4 0.49 23.1 0.31 109. 0.58 255 . 0.38 96.6 0.58 190. 1.18 13.5 0.32 2.7 0.25 65900 0.138 10 7 8 5 2. 18x10 17 -3 4 .2 1x 10 0.113 -6 2.48x10 21.2 10 0.020 44.4 67.8 14.4 30.7 6.80 137 . 9 10 7 9 7 9 1.17x10 -10 1.17x10 0.044 -4 3.39x10 0.450 12.8 8 0.120 38 .6 8.6 89.2 4.753 32.1 17.811 25.2 24.8 42.0 2.84 71.2 7 8 2.29x10 0.380 6 0 7 5 0 -6 12.2 7 0.690 5.62x10 -3 6.72x10 -3 2. 95x10 -3 3.22x10 -8 5.85x10 0.724 -13 2.367x10 0.093 133. 17.9 95.5 85.8 62.5 7.9 3 6.6 9 .9 16.6 34.4 6 0 9 7 9 0.035 6 9 8 5 5 6 10 9 4 6 9 5 0 -14 1 . 1 10x10 -9 1 . 189x10 0.539 2.2 2x10~ 0.128 0.055 -6 2.012x10 KEY : H q ■= no evidence to suggest that sample is not from a normal population S i gnificance level of acceptance; a ■= 2.5% b = 5% c •= 10% d = <1% X = mean value, SD ■= standard d ev iation, X' = c hi - s q ua r ed value, DF “ degrees of freedom 30 50 25 40 20 30 I* E 20 = 10 10 5 0 m m r r i ________ ................. 3.5 4 i » 4.5 t i i i i t 5 i i 0 i 4.5 5.5 A-l. Histograms 5.5 Log Cl ( m g / l ) L o g Na ( m g / l ) Figure 5 of Na and Cl (mg/l) concentrations. Lo g Na ( m g / l ) Figure A-2. L og -p ro bability plots c oncen trfftions. _J____ » » i iJ 4.4 0 OJ 5.6 4.7 L o g Cl ( m g / l ) of Na and Cl (mg/l) 158 AVERAGE BRINE COMPOSITION Table A-2 means lists the formation water means (geometric and an unbiased estimator of the me a n ) , maximum and minimum concentrations, variances sample listed sizes. Also (unbiased estimator), and are seawater concentration ratios, defined as: SWR= average brine value/seawater value, and evaporation factors, defined as E F = (concentration ratio of a given constituent/concentration ratio of B r ) . values are are given from Brewer Seawater in parentheses next to each element, (1975). Averages and standard and deviations calculated from log transformed data represent the geometric means and geometric variances, respectively. The geometric mean may be the preferred estimator of the population means and variance when deviation/mean) and Link means and and have unbiased the is less than 1.2, (1971). exist smallest estimators. that variation estimators are sampling These of (standard a rule suggested by Koch However, other variances the coefficient of population statistically error statistics variance are termed unbiased of all minimum variance unbiased estimators. Generally, unbiased estimators of means are preferred if the lognormal skewed, as is observed for Na and Cl values distribution is (Gilbert, 1987). The unbiased estimates of the population means and variances are calculated using: (2y) m = [exp (y) ] X n (1/2 Su 2 ) and V=exp [Xn (su 2/ 2 ) ]-Xn [su 2 (n-2) / (n-1)] where y=geometric mean, su 2= geometric variance, n=number of observations, and the 159 TABLE A-2 SUMMARY STATISTICS TRV BEREA (29) n (3) Cl (19,350 mq/kq) 194000 172000 A 175000 B 195000 10000 15600 C 176000 D 13600 209000 196000 E SWR 10. 0 8.1 EF 0.48 0.54 DD (40) RP (13) DT. R (2) N/8 (26) TBR (11) 171000 173000 3430 120000 212000 8.8 0. 59 194000 194000 2070 75800 242000 10.0 0.32 212000 212000 3720 179000 251000 10. 9 0.22 210000 214000 8180 117000 265000 10.8 0.33 12600 12800 6219 91000 16300' 6.5 0.42 Br (67 mq/kq) 1400 A B 1460 C 295 940 D E 1840 SWR 20 .8 EF 1 1100 1240 164 590 2340 14 .9 1 1000 1090 74 .0 315 2390 14 .9 1 2100 2300 308 1050 4210 31.3 1 3400 3400 345 3060 3750 50.9 1 2400 2400 202 690 3340 32.8 1 1030 1050 63 .0 750 1430 15.7 1 Ca (411 mq/kq) 45100 A B 45400 C 3660 D 38400 49500 E SWR 110. 5.3 EF 29000 33300 4790 11600 67700 63.0 4.2 24500 27100 2020 7390 7330 59.6 4.0 65200 68600 6440 27800 96200 158. 5.0 88000 89700 17300 72400 107000 214. 4.20 74000 76900 4290 35200 124000 180. 5.5 22800 23300 1530 15800 35500 55. 5 3 .5 Mcr (1290 mq/kq) A 8250 B 8270 C 355. D 7600 E 8790 SWR 6.4 EF 0. 30 6600 6810 630. 3840 9700 4.7 0.31 5100 5360 284 . 1820 11300 3.9 0.26 8700 9220 939. 3370 14600 6.7 0.21 11800 11800 1450 10400 13300 9.1 0.18 11500 12100 763. 6080 20000 8.9 0.27 5130 5280 410. 3200 9110 3 .9 0.25 71000 72400 2340 38800 103000 6.6 0.44 34200 37100 4370 12400 61500 3.2 0.10 23100 23100 900. 22200 24000 2.1 0.04 31400 33500 2500 9820 48800 2.9 0. 088 47300 47700 1890 37200 59000 4.4 0.28 Na (10760 mq/kq) A 63000 68200 B 63100 70100 C 2580 6250 D 58200 43000 E 66700 88700 SWR 5.9 5.8 0.39 EF 0.28 160 TABLE A-2 (cont'd.). U. ). DD RF DT. R N/S TBR 1660 1910 264. 440. 4750 3.8 0.26 1640 2010 220. 380. 8360 4 .1 0.27 7200 7930 1035 3570 13300 18. 0.58 13400 14300 5020 9270 19300 33.6 0.66 9250 11000 1400 2300 24100 23.2 0.71 3680 3780 272 . 2180 5440 9.2 0.59 1060 1260 195. 350 2920 117 7.9 780 911. 86.0 170. 2350 98 6.5 1970 2440 487 . 290. 3980 246 7 .8 2680 2710 365. 2340 3070 335 6.6 2190 2430 230. 800. 6030 274 8.4 750. 766. 43.0 540. 1040 94 . 6.0 Rb (0.12 mg/kg) 3.6 3.7 A B 3 .6 5.6 C 0.2 1.7 D 3.4 0.4 E 17.2 3.9 SWR 30. 30.8 EF 1.4 2.1 3 .0 4 .2 0.7 0.4 11. 1 25. 1.7 12 .4 13.6 1.9 6.5 23.8 103 3.3 37 .3 37 .5 3.7 33.8 41.2 310 6.1 24. 1 30.1 5.3 10.7 77.7 200 6.1 7 .9 8.3 1.2 4 .5 11. 66. 4.2 Li (0.18 mg/kg) 8.0 29.3 A 8.0 B 33.7 * C 4.6 D 8.0 9.2 E 8.0 81.0 SWR 44. 150 2.1 EF 10. 23 .9 31.8 4.2 2.0 68 .0 133 8.9 46.5 48.4 3.9 24.0 76.0 258 8.2 92 .9 96. 0 24 .0 72.0 102 . 516 10. 59.2 63.9 5.2 18.0 101. 330 10. 37 .5 38 .1 2 .1 26.0 47.0 210 13 . B (4.5 mg/kg) A B C D E SWR EF 21 43 13 1 85 4 .6 0.31 119 150 37 39 377 27. 0.85 226 260 120 134 383 50. 1.0 127 170 34 25 498 28.3 0.9 13 14 2 6 21 2.9 0.20 BEREA K. (399 mg/_kgl_ A 640. 640. B C 35.0 D 580. 700. E SWR 1.6 EF 0.075 sr (8 mg/kg) A 2000 2000 B 114. C D 1780 E 2140 SWR 250 EF 12 . TRV 28 40 13 18 117 6.4 0.43 161 TABLE A-2 (cont'd.). BEREA TRV Si (0.5-10 ma/kg) A 3.2 8 B 3.4 1 C 90 50 D 4 4 E 4 2 61 SWR 53 EF 031 036 DD________ RF________ DT. R .34 2.6 2 2.9 0.30 2.,7 .60 0. 0. .90 0.30 8.5 0. 4t> 0.015 29 228 228 230 240 115 400 31 51 1.2 . 11 6 0. 49 0. 033 N/S TBR 2 . 3 37 .007 5 30 0.90 6.3 42 013 0.70 7 63 040 550 590 570 441 690 547 620 600 235 1087 80 80 85 45 126 160 180 210 210 110 100 90 150 42 38 41 1.6 n h 4n A ~ B C D E HCOj A ~ B C D E SWR EF 74 77 80 50 126 125 129 130 76 193 (142 mq/kq) 11 85 20 45 6 16 10 25. 0.14 0. 007 110 120 0.022 43 45 390 1.4 0. 042 330 1.5 0.030 0. 032 180 300 57 1200 1200 1200 10 49 28 26 66 11 20 0 0 0 100 1130 350 0.44 0. 013 50 0.037 0.0007 150 0. 018 720 0.076 0 .005 25 28 3 7 65 420 13 345000 352000 14000 196000 444000 10. 0.28 10 0 0 160 0.32 0. 017 SO, (2710 ma/kq) A 45 65 B 71 130 C 43 35 D 10 0 E 100 610 SWR 0.017 0.023 EF 0.001 0.001 I (.06 mg/kg) A 23 B 23 C 3 D 17 E 28 SWR 380 EF 18 107 140 0.36 0.66 0. 004 11 11 13 13 23 28 2 1 0 28 6 10 68 4 71 170 11 TDS (35.000 ma/kg) A 315000 282000 B 316000 289000 C 16400 26100 D 284000 21500 E 335000 326000 SWR 9.0 7.4 EF 0.43 0.50 180 380 12 12 38 41 16 25 57 630 13 278000 280000 5570 197000 349000 7.9 0.49 296000 315000 31900 125000 395000 8.5 0.27 355000 360000 61400 299000 421000 10. 0.20 0 610 1.1 . 0 001 6 25 90 0.29 0.018 205 250 51 11 12 1 6 26 180 12 207000 210000 10100 151000 273000 5.9 0.38 162 TABLE A-2 (cont'd MC1„ A “ B C D E SWR EF TRV BEREA (69.2 mea/ka) 2980 1840 2220 2990 274 . 213. 2580 102 . 3240 4240 4 3. 26.6 2.0 1.7 DD RF DT. R N/S TBR 1660 1810 122. 573. 4640 23.9 1.6 4020 4240 403. 1680 6010 58.0 1.8 5420 5520 1010 4525 6500 78.3 1.6 4720 4890 262. 2290 7380 68.2 2.1 1580 1610 106. 1060 2540 23. 1.5 KEY; All values in mg/l unless noted A: Geometric mean B: Minimum variance unbiased estimator of population mean C: Unbiased estimator of standard eviation D: Minimum value E: Maximun value SWR: Seawater ratio; average brine value(B)/seawater value EF: SRW/ Br seawater ratio MCL2 : Mg + Ca + Sr - O.SHCO^ - S04 (meq/1) n: Number of analyses for major components TRV: Traverse N/S: Niagara/Salina DD: Dundee RF: Richfield DT. R: Detroit River TBR: Trenton Black River 163 function Xn is from statistical tables or calculated by the following equation from Gilbert (1987): Xn (x) = 1 + (n-1)x/n + (n-1)3x2/ (2!*n2 (n+1)) + (n-1)5x 3/ (3!n3 (n+l)(n+3))... , COMPARISON WITH SEAWATER The average compared with Figure A - 3 . brine the compositions chemistry of from Table evaporating A-2 are seawater in The seawater data from McCaffrey et a l . (1988) are used in this figure. Inspection of this diagram shows the relative degree of agreement that exists between these brine components and seawater. be compared with seawater The brine chemistry can also by examining concentration ratios listed in Table A - 2 . the seawater These ratios help to quantitatively illustrate the changes that seawater would have to undergo brine. For average brine if it were to example, based salinity on evolve brine ranges from into Michigan salinity 5X to basin (TDS), the 10X that of seawater depending upon formation, with a maximum of 1 2 .6x. If the brine had originated from seawater and no mineralogic reactions had affected them, then each element concentration ratio (brine ratio, at clearly not value/seawater least the various degrees within case, value) should individual as some (Br, Ca, Mg, Na, equal formations. elements K, Sr,Rb, are Li, the TDS This is enriched to B, I) while other are depleted to various degrees (alkalinity, S04 , S i ) . This type demonstrate of evidence that has formation been brine used is not in the simply past to unaltered 164 F i g u r e A-3. Average Michigan formation brine compostion (log mg/l) com pa re d with s e a w a t e r ( da sh ed line). S e a w a t e r d a t a f r o m M c C a f f r e y et al. ( 1 9 8 8 ) . 165 5.6 .4.6 6 .5 1 Log No O #5° 5] X / fXTv 4 JS ®n 4.5] 4 4.6 | ~<5 4 A A *o ^3.5 o 3 _l | 2.5 5.5] o 5 O ?4.5| CP 4 .5 1 I «no 4 o> o 3.5 _l u»3.5 u O * JE k . (/) o» j2-5! _i r*r 2 ___1----- 1---- 3.5 25 3 Log Br ( mQ / l ) O O BEREA TRAVERSE • DUNDEE ■ R IC H F IE L D A D E T R O I T R. O N IA G A R A / S A L IN A A. O R D O V I C I A N 166 seawater (Chave, 1960; Collins, 1975). However, salinity is not the best reference to judge the alterations. to better judge depletions, the magnitude 1975), concentration factor: EF= is enrichments or In this study, as in others assumed can be (concentration conservative, used to ratio ratio of Br) factor, S r , Rb, Br ratio concentration excess the a concentration ratio of a conservative element must be used as a reference. (Collins, of In order calculate of a (Collins, given an its excess constituent/ 1975). Based on the elements enriched over seawater Li, I . and include Ca, Elements depleted from seawater are C l , Mg, Na, K , alkalinity (HC03) , S04 , and T D S . Boron and MC12 (Ca + + are Mg Sr - 0.5HC03-S04 conservative with, to Br. Both enrichments meq/1) approximately or only slightly enriched, Chapter and in 1 and depletions chapter with respect 2 explain generally that reflect these water-rock reactions. FORMATION COMPARISON Univariate statistical methods are used to test equality of water chemistry between different aquifers, from different areas well over time (NCASI, 1985). to equality test formations. similarities within This of an aquifer, in from a single The Student's t-test is used here mean comparison found or brine brine concentration is warranted chemistry between in light using methods described earlier (Chapter 1, Chapter 2). of the graphical 167 Before applying the Student's t-test, equality of variances must be demonstrated by the F-test, using a null hypothesis Ho: components meeting significance using a s22= s l2 ' or null populations. with the better, F-test the hypothesis s2=variance. at the Student's For 0.01 t-test Ho:u2=u1 , where those level was u=mean of applied of sample Not rejecting H0 suggests that no statistical evidence exists to suggest the means are different, while rejection of H Q suggests that there is statistical evidence for a difference in m e a n s . For this test, means of the Berea, Traverse, and Dundee were first compared to establish if this group of samples could be combined. Generally, the t-test results showed that means appear similar of the major several between each elements formation. in the However, Traverse samples exhibit a high degree of variance, which caused Br, Cl, Na, Ca, and Dundee TDS, to samples fail were the used to formation water chemistry Table summary A - 3is a components and ratios Generally, most elements F-test. represent for of that Because the of upper intraformational the t-test meet passed results the at F-test the this, the Devonian testing. for the criteria. 0.05level of significance for the F- and T-test, respectively. Inspection of Table A-3 shows the following: (1) mean concentrations in the Dundee and Traverse formation samples can be considered statistically similar in the cases where the t-test is applicable. Many of the intraformation TABLE A-3 STUDENT'S t-TEST 'RESULTS FORMATION DDTR DDRF DDNS DDTBR RFNS R R R R R R R R R R R R R R R NR R R NR NR R NR R R R NR R R R NR NR R R R NR R R R R NR NR NR NR NR NR R NR NR R NR NR NR NR R R R R R NR R R R NR R NR R NR NR NR RFTBR TB! NS COMPONENT Br Cl Na Ca Mg K Sr Rb Li B I si NH4N so4 hco3 TDS D 180 NR NR NR NR NR NR NR NR NR R R NR NR NR NR NR NR NR R NR R R R R R R R R R R R R NR R R R R NR NR KEY: H0 = mean-L = mean, NR, R = not rejected, rejected at the level of significance of at least 0.01 for the F-test, and the 95% to 99% confidence level for the T-test, depending on F-test results Blank = t-test not applicable due to rejection by F-test at the 0.01 level of significance FORMATION CODES: DD= Dundee, TR = Traverse-Berea, RF = Richfield-Detroit River, NS = Niagara-Salina, TBR = Trenton -Black River 169 comparisons made using the Dundee samples apply for Traverse samples as well, in the Richfield-Detroit River brine can be considered similar, were found to (2) Mean concentrations brine (3) and Niagara/Salina Mean concentrations in the Richfield, Detroit River, and Niagara/Salina samples are statistically and (4) different Mean silica from (Si) the Traverse-Dundee and deuterium (D) samples; concentrations are statistically similar between all formation samples. These results suggests that two groups of brine exists, the lesser concentrated water from the Berea, Dundee water and the more highly Traverse, and concentrated Richfield, Detroit River and Niagara/Salina formation waters CORRELATION COEFFICIENTS Correlation relationship correlation, might be and Cl are between A or negative, the degree of high degree of between elements suggestive of a common control. For example, Na concentrations would correlate positively when both Alternatively, only inversely equilibria, as by strong equilibrium. correlate Ca decrease in sulfate. helpful measure variables. either positive supplied mineral coefficients the inverse For when cannot dissolution correlations example, Ca2+ controlled only increase of might and by without halite. suggest S042= would CaS04 mineral a concomitant Although correlation coefficients are in reducing geochemical data, elemental correlation is not evidence of causation (Egleson and Querio, 1969). 170 Table A-4 logtransformed is a data correlation by the SAS matrix generated program. The for the closer a correlation coefficient is to ^ 1 , the more the variables are related. The following is a summary of significant correlations from Table A - 4 . COMPONENT pH Br Cl Ca HCO3 I K Li Mg Na so4 Sr Rb Cs B Si TDS Several + CORRELATION CORRELATION Cl, so4 Mg Rb, Ca, K Na, S04 S04 , pH TDS, Mg Sr, K, Rb,Mg S04 , Na NONE so4 Na, S04 Ca, Sr, Rb Ca, Rb, B, Sr Na, S04 B, K, Br, Rb Na, S04 Ca, Sr, K, Br S04 , pH so4 Cs, Rb, K Na S r , Ca Ca, K, Mg S04 , Na K, Ca, Cs, Sr,Br Na Rb, K, Br Na K, Rb, Li Na NONE HCO3 Cl pH, S04 correlations are noted in this reoccurring inverse correlation exists between many of the other elements. clear, but may reflect concentrations are samples. other Two found notable the the most lowest highly correlations are A (Na,S04 ) and The meaning of this that in table. S04 is not and Na concentrated between HCO3 , and TDS-C1, which might represent "basic" pairs, Sithat is, each are more highly correlated with each other than any TABLE A-4 Correlation matrix log-transformed data. PH BR CL CA HC03 I K LI MG NA SO* S« a SI TOS MG 1.00000 -0.397*5 -0.51536 -0.36*38 0.35092 - C . 2*392 -0.29*16 -0.06310 -0.37018 0.09390 0.*7277 - C . 29159 - 0 . 3 l q23 -0.13211 -0.171*2 -0.16636 -0.*9935 -0.297*5 1.00000 0 . * 2 713 0.78716 -0.2551* 0 . 38 30 6 0.73060 0 . 7 1279 0.7*98* -0.*6562 -0.4*378 0.7C307 0.83975 0.7570* 0.701*7 0.27602 0.27669 -0.51636 0.42713 1 .oooco 0.56032 -0.37858 0.47153 0.42915 0.395B7 0 . 6 6 5 0* 0.18757 -0.52 *1 * 0.51537 0.39905 0.0*299 0.21127 -0.05950 0.77501 - C . 36*33 0.78716 0.56032 1.00000 -0.2*165 0.63511 0 . 9*t 59 I 0.7111* 0.89699 -0.65677 -0.69076 0.95165 0.90696 0.7061 * 0.78612 0.29576 0.39155 0.35092 -0 •2 55i* -0.37 85 8 -0.2*165 I . 00000 -0.10 2*2 -0.23808 -0.00 01 * -0.32052 0.0*931 0.33815 -0.20803 -0.22176 -0.11275 0.03337 -0.51067 -0.36*76 -0.2*382 0.38306 0.47153 C . 63511 - 0 . 10 2* 2 1.00000 0 . 57 760 0.491*8 0.59988 -0.38150 -0.35*50 0.62891 0.61593 0.*0263 0.53619 0.01753 0.46821 -0.28*16 0.78060 0.42915 0.9*591 -0.23308 0.57760 l . COOOC 0.76103 0.76860 -0.71112 -0.62208 0.88565 0.9*146 0.77362 0.8792* 0.43*57 0.32191 -0.06310 0.71279 0.29597 0 . 7 111* -0.0C 01* 0.*91*8 0.76103 1.00000 0.48781 -0.35199 -0.29753 0.65719 0.70070 0.5*22* 0.81678 0.02962 0.23*69 -0.57018 0.7498* 0.685C* 0.99699 - 0 . 3 2 n 52 0.59988 0.76960 0.48791 1.00000 -0.465*8 -0.69666 0.36333 0.77237 0.530*2 0.55*88 0.17223 0.53576 3 SI TOS -0.171*2 0.701*7 0.21127 0.78612 0.03337 0.53619 0.8792* 0.91678 0.55*88 -0.6*378 -0.33838 0.69*76 0.8*393 0.7*608 1.00000 0.238*1 0.12871 -0.16636 0.27602 -0.05950 0.29576 -0.51067 0.01758 0.43*57 0.02962 0.17223 -0.48192 -0.26296 0.29097 0.41108 0.48577 0.238*1 1.00000 -0.03510 -0.49935 0.27669 0.77501 C . 39155 -0.36*76 0.46821 0.32191 0.23*69 0.53576 0.1*07* -0.48709 0.36*32 0.296*0 -0.01327 C . 1 2 97 1 -0.03510 l.OOOCC NA PH BR CL CA HC03 I K LI MG NA SO* SR RB CS B SI TOS 0.09390 -0.46562 C . 10757 -0.65677 0.0*931 -0.38150 -0.71112 -0.35199 -0.465*8 I . 00000 0.5009b -0.66066 -0.7160* -0.76989 -0.6*379 -0.*9192 0.1*07* SR R9 - 0 . 2 3159 0.*7277 0.70307 - 0 . * * 37 8 0.51537 -0.52 *1 * 0.95165 -0.69076 -0.20803 0.3391 5 0.62891 -0.35*50 0.99565 -0.62203 0 . 6 5 7 L9 -0.29753 -0 .6 9 6 6 6 ‘ 0.96333 -0.66066 0.50096 -0.70*06 I . 00000 L.0C000 -0.70*06 0.9*562 - 0 . 5 * 0 16 0 . 6 7°53 -0.33165 0.69*76 -0.33838 0.29097 -0.26296 0.36*32 -0.48709 -0.31923 0.33875 0.39805 0.90696 -0.22176 0.61593 0.941*6 0.70070 0.77237 -0.7160* -0.5*01 6 0 ®8■♦562 1 .CuOOO 0.89302 0.8*393 0.41108 0.296*0 SO* . CS -0.13211 0.7570* 0.0*288 0.7061* - 0 . 11275 0.40263 0.77362 0.5*22* 0.530*2 -0.76989 -0.33165 0.67953 0.89302 I . 00000 0.7*608 0.48577 -0.01327 171 R9 CS I PH HCO 3 LI CL CA K BR 172 of the remaining variables. The meaning of these relationships are explored further using the R-mode analysis discussed Egleson pairs below. It and Querio in the correlation is (1969) Sylvania not also interesting note report KC1-B and Br-I Formation found to in the brine from that are basic Michigan, a present study. Finally, elements with similar geochemical behaviors are observed to correlate together, for example, Ca-Mg-Sr and K-Rb-Cs. MULTIVARIATE STATISTICS Multivariate statistical tests of Q-mode and R-mode factor analysis were conducted on the data set in order to evaluate population homogeneity possible geochemical controls. reduce the measured interpretable determine together that possible. of m called best-fit describe In other words, variables (chemical to help much a fewer factors. factors as to elucidate Factor analysis attempts to variables variables, the and by of The grouping the data number goal is of to variables variance as factor analysis combines the set components or wells) into the p number of best fit, mutually uncorrelated factors, with p 4,l,B U.K Depth,Sr Na Spec. Gr. Ca NH3,I Mg,Na,K,U,Sr Br,B,SQ4,Rb, Depth Mg-PRI,Ca/Mg Ca Sr.Spoc. Gr. Mg-PRI,Ca Br,NH3,l,U K,8 Fe,Br,Rb, Spec. Gr. Ca/Mg (V a r i m a x results factor analysis ,,n c o \ 9 for - eson and Querio ( 1 9 66 99 ) from Egl Michigan Sandstone formation waters, 1 75 Mg Spec Gr.,S04 Na Fe Depth Mg,U,Sr,Br,B NH3,l,S04,Hb 176 Figure A-5. R - m o d e f a c to r a n a l y s i s r e s u l t s f r o m H i t c h o n et a l . (1971), for W e s t C an a d a b as i n w a t e r s . TOP: varimax rotation, BOTTOM: bi-quartum oblique rotation . 177 Hitchon et al . (1971) R-MODE VARIMAX ROTATION K .U .R b Cl.C a.M o .N a.S T Br.TDS Na.Sr 4 K ,U ,M g .R b CI,Ca,N a,Sr,TD S Br Hitchon et al. (1971) R-HODE B1QU ART I MIN OBLIQUE ROTATION. Figure A-5 178 Figure A - 6 . R - m o d e f a c t o r a n a l y s i s r e s u l t s fro m L o n g et a l . ( 1 9 8 6 ) f o r n e a r - s u r f a c e s a l i n e g r o u n d w a t e r s in M ichi g a n . 179 Long a l. et 1 R-MODE 2 N l.C I COND K - (1986) NH, — Mn - - - Fe Mn _ ROTATION 3 Ca Mg - VAR1MAX ALK SI K Co Mg Fe F,pH SI,Zn s o 4,n h . COND Cl s o 4 ,a l k ,si nh 4 pH,Fe,Zn Na.ALK Na,CI,F,Mn Mg,COND,Ca PH K F so4 ----------------------— 1 2 Na,Cl,COND K Ca Mg NH. Ca.Mn Mg 3 Mn Fe K ALK.Si COND Fe NH4 ,Zn Na.Cl S 04 so4 - nh4 Si F.pH.Fe.Zn ALK,F,pH ALK Mn SI PH Mg.Na.CI Ca.COND k ,s o 4 F - • Long et al. - (1986) R-MODE Figure »-6 - - PROMAX ROTATION 180 Egleson and Querio (1969) conducted R-mode factor analysis (varimax rotation) on the Sylvania Formation waters from the Michigan basin. Both chemical and physical data were used, but it is not clear if their data were first logtransformed found to first before account factor had analysis. for Although 100% of the interpretable data ten factors variance, loadings; the were only the remaining factors had high loadings on only a single element. Their first factor showed high loadings for the minor elements and production depth, interpreted to reflect a common source related to paleotopography. Hitchon et a l . (1971) used R and Q-mode factor analysis to study West Canada sedimentary basin formation waters. mode factor analysis showed their data are homogeneous. variation in the Q-mode results were combined with QThe flow direction and depth and used as evidence for shale membrane filtration. R-mode factor analysis was without the partialling out of salinity, oblique rotation methods. was conducted preformed both using varimax and A second R-mode factor analysis combining the results from the first R-mode test with physical parameters and stable isotopic data. The R-mode results were interpreted as evidence that the brine originated from seawater modified by shale membrane filtration. Long et al. (1986) analysis to study saline, mid-Michigan area. used both Q and R-mode factor near-surface groundwaters in the Although the Q-mode results demonstrated 181 a single population scores suggested of water two types exists, the extracted of waters, a normal Q-mode background (regional) water and localized saline water. Q-mode scores were saline contoured infiltration. to delineate areas of water Four different R-mode rotation methods were used, with similar factors produced by each method. Factors were factor, interpreted to show: (1) a saline water indicating brine input, (2 ) a water-rock factor, carbonate, halogen oxide, factor and clay reflecting mineral reactions, sulfate reduction reflecting (3) and a non­ silicate interactions. FACTOR PATTERNS These factor loadings processes. and the loading studies can Kramer processes between suggests mineral anion-anion reactions, single or and factor provide be anions might and in light several a represent: cations of (2) a direct cation-cation suggests illustrations of of how geologic outlined several general patterns equilibria, (3) good interpreted (1969) they a might or inverse minerals loading loading source an common represent variables common (1 ) between ion-exchange highly origin. in a In addition to these patterns, the other studies have suggested the following interpretations of factor pattern . A common source: Hitchon et a l . (1971) interpreted the high loadings on Li, Rb, K, T D S , Mg, Ca, Na, Cl, Sr, Br, and S04 in their first R-mode factor common origin for these (Figure A-5) elements, seawater. as showing a A similar 182 interpretation of many elements loading together in a single factor was made by Egleson and Querio (1969) Mixing of waters: (Figure A - 4 ) . The correlation between the first Q- mode factor with decreasing salinity was used by Hitchon et al. (1971) (1986) Na, to support dilution by freshwater. Long et a l . interpreted an R-mode factor showing high loadings on Cl, K, conductivity, Ca, Mg, NH 3 to and reflect input and mixing of saline water (Figure A - 6) . of their first Q-mode factor, having a the Contour maps high loading on alkalinity, revealed the location of brine inputs. Membrane filtration: second Q-mode interpreted membrane by factor in Hitchon filtration. The increasing importance of the a et High down-dip al. flow (1971) loadings to of Mn, and high negative loadings on Cu, Na, direction reflect Rb, was shale S r , and Zn, C l , HCC>3 , and TDS in this factor for downflow samples suggested that metal rich, lower salinity ground waters exit the outflow side of shale layers. In their R-mode analysis combining chemical and physical data, high positive loadings on the seawater factor (factor 1, Figure A-5) of temperature, depth, pressure, and SD, opposed by high negative loadings on pH, was thought to reflect increased membrane efficiency with dept h, pressure, and temperature, as well as the isotope mixing hypothesis of Hitchon and Friedman (1969). Dissolution of halite or other minerals: other data, positive Hitchon loading on et al. both (1971) Na and thought Cl In addition to that suggested a weak halite 183 dissolution (Figure A - 5 ) . This pattern is in contrast to factors interpreted to show mineral equilibria, inverse loadings of common mineral components which show (Kramer, 1969; Long et al., 1986). Dolomitization: evidence thought in their results that high positive seawater factor with dolomitization. Kramer Hitchon This to al. (1971) suggest loadings TDS is et little dolomitization, of Ca partialled consistent found and out with Mg in may the but the reflect findings of (1969), who interpreted high positive loadings on Ca and Mg coupled with a negative loading on HC03 as reflecting dolomitization. and HC03 are Feth Similar bipolar factor loadings of Ca, Mg, also reported by Collins ^1967), and Long et a l . (1986). Ca-Mg pattern is associated with these studies supported and Although this typical dolomitization, studies have not found this result, in (1969a) , Dawdy several even though other data dolomitization (Collins, 1969 ; Lee, 1969; Egleson and Querio, 1969). Sulfate alkalinity reduction: and sulfide Bacterial was reduction thought to be of sulfate to represented by bipolar loadings on pH2S and S04 by Hitchon et a l . (1971) . Long et between al (1986) interpreted alkalinity reduction (Figure and a sulfate strong to bipolar represent loading sulfate A-6). Formation of chlorite: An inverse loadings of Mg and Fe was interpreted by Hitchon et chlorite formation (Figure A-5). al. (1971) to represent 184 Cation exchange: The bipolar loadings of Ca and Na in the R-mode results with salinity partialled out was thought by Hitchon et al. A-5). Also, decreasing Rb>K>Sr>Li>Mg because this cations on (1971) to reflect cation exchange were factor thought to loadings represent is exactly the order of clays (decreasing in (Figure the cation order exchange, "replacing” power of non-hydrated ionic radius, increasing hydrated ionic radius, and polarizability). Contribution from organic matter: Hitchon et al. concluded that similar factor scores represent an organic material source negative loadings of I , Br, and for Br and (Figure A - 5 ) . NH3 , and the (1971) I might Highly correlation between I , B r , and production depth in a single factor were interpreted halogen by source Egleson and from organic Querio debris (1969) to reflect in topographically a low areas of the Sylvania Formation (Figure A - 4 ) . Mineral equilibria Hitchon et a l . (1971) S04 along with high control: Both Kramer (1969) and interpreted high loadings of HC03 and negative loadings of Ca, Mg, and Sr (with salinity partialled out) to reflect dolomite, calcite, and celestite equilibrium. loadings of Ba and S04 Kramer reflect (1969) barite suggested inverse equilibrium. An inverse loadings on Sr and S04 was also found by Egleson and Querio (1969) inverse (Figure A - 4 ) . loadings of Si Long et a l . (1986) and K to interpreted represent silicate interactions (Figure A - 6) . Equilibrium was also supported by chemical model calculations. Kramer (1969) interpreted both 185 the inverse cations), loading and of Si positive and Cl pH-Si02 (thought to loadings represent to represent aluminosilicate equilibrium. Q-MODE METHODS AND RESULTS Q-mode factor analysis was preformed in this study using the SAS statistical program on the IBM 4381 computer at Michigan State University. transformed similarity the theta cosine A matrix was coefficient of non-standardized used, constructed proportional logusing similarity suggested by Davis (1986). The principal factor solution for the first five Q-mode factors, their eigenvalues, total variance, and the cumulative percentages of variance are listed below. Factor 1 2 3 4 5 Eigenvalue 140.7 0.558 0.354 0.202 0.714 Difference 14 0.2 0.204 0.151 0.132 0.033 Proportions 0.991 0. 004 0.003 0.001 0.001 Cumulative % 0.991 0.995 0.998 0.999 0.999 The first variance of the from a analysis single can be eigenvector data, accounts for over strongly suggesting that homogeneous conducted 99% of the data are population, and that using the the entire data R-mode set. A single eigenvector explaining such a large percentage of the 186 data variance implies that a single gradient characterizes the This samples. is interpreted as a salinity gradient, similar to the interpretations of Hitchon et al. (1971) and Long et a l . (1986). Davis (1986) suggests that a dominant first factor is often obtained in Q-mode analysis, such as is the case here. Such a dominant factor reveals little about the structure of the data, second and and magnitude is considered third and a "nuisance" eigenvectors, accounting for although small factor". much This was the case for Hitchon et al. the whose variance. (Davis, and factor accounted The amount of in the 2.986) . first for Long et first Q-mode extreme of (1971) , whose factor accounted for 55% of the variance, a l . (1986) smaller proportions variance, may reveal more useful information The for 95% variance of (>99%) explained by the first factor in the present study, however, suggests that further Q-mode factoring may not be warranted. R-MODE FACTOR METHODS R-mode factor transformed available data on University. the The analysis set, using IBM 4381 review of was preformed the SAS computer other on the statistical at factor package Michigan analysis log- State studies demonstrated three problems that might be encountered in the R-mode factor analysis of brines, this study. Firstly, which were considered salinity might dominant the in factors, as was suggested by the Q-mode analysis and by the results of Hitchon et al. (1971). In order evaluate the effects of 187 salinity in the present study, TDS was partialled out of the R-mode analysis. A comparison of the effects discussed below. Secondly, of this are missing or erroneous variables might bias factors, especially if the variable represents an important species such as pH. Many of the samples obtained from outside this study (M.D.N.R. and oil company open file data) did study. not To report address were evaluated, minor this components concern, two measured subsets of (1) the entire data set was used in this the data including samples with missing data, and (2 ) only those samples having complete data. the resulting A-5, case because No difference were factors using either data la, the and pH A-5 case lb) . measurements concentrated waters, and without found are In in the makeup set a suspect (compare Table similar in the R-mode analysis was including the pH data. of fashion, these highly run both with Slight differences in the makeup of the extracted factors were found when pH was included, which is discussed below. R-MODE RESULTS Table A-5 reports the eigenvectors, communalities, and factor scores combinations data. of diagrammatically in for each of the different The Figures eigenvalues, results A-7 to are A-10. displayed Components plotting towards either end of these diagrams have approaching promax shown; — 1. rotation The results principal of the component, following loading varimax, four trials and are 188 Case 1 (results samples having pH study) are used, shown in Figure A-7): only those (generally only samples collected in this pH variable is included, and TDS is not partialled out. Case lb is (not shown): all samples are used, pH variable included, and TDS is not partialled out. Results are listed in Table A-5 for comparison with case 1. Case 2 (Figure A - 8) : All samples are used, pH variable is included, and TDS is partialled out. Case 3 (Figure A - 9 ) : All samples are used, pH variable is not included, and TDS is partialled out. Case 4 (Figure A-1 0) : All samples are used, pH variable is not included, TDS is not partialled out. The eigenvalues, that has been representing the variance in the data extracted onto each factor, factors account for 90 to 92% of the variance (Table After A-5). the fourth factor, show that 4 in the data the amount of variance explained be each factor drops to less than 3% of the variance, well below the estimated experimental error for the components. Communalities (Table A - 5 ) , a measure of the efficiency that each variable and show the factors variability in the data. are is explained, efficient in are explaining >0.75 the Exceptions are pH, alkalinity, and I, having communalities near 0.5. This could signify that additional factors need to be extracted in order to better explain these later variables. 189 TABLE A-5 R-MODE FACTOR ANALYSIS RESULTS Case 1) Only samples with pH are used pH variable included TDS not partialled out 1 Factor Eigenvalue Difference Proportion Cummlative 9.117 6.597 0.5960 0.5960 COMMUNALITIES PH .5177 Aik .5372 MG .8931 RB .9598 TDS .6799 TOTAL 13.8118 BR I NA CS 2 2.5206 1.0682 0.1648 0.7608 .8189 .5404 .9797 .8789 A) PRINCIPAL FACTORS FACTOR 1_______FACTOR 2 CA .9761 PH .9636 K .9636 .4976 CS RB .9582 B .3463 SR .9279 Aik .3335 MG .8810 S04 .3018 BR .8352 SI .2571 B .8118 .1848 RB CS .7759 .1476 K LI .7254 LI .1405 I .6451 BR .07602 CL .5455 SR -.0022 TDS .4224 -.0171 CA SI .3652 I -.1473 Aik -.2861 MG -.3128 PH -.4216 NA -.5646 NA -.6708 TDS -.7060 S04 -.6839 CL -.7767 CL K S04 B 3 1.4524 0.7109 0.0949 0.8557 0.74145 0.2657 0.0485 0.9042 .9469 .9520 .7611 .8604 CA LI SR SI FACTOR 3 Aik .5173 LI .4984 PH .2892 S04 .2765 B .2737 NA .2656 I .2580 CL .1573 BR .0678 CA .0539 TDS .0456 SR .0366 K .0075 RB -.0014 MG -.0249 CS -.1103 SI -.7181 5 0.4757 0.4570 0.0311 0.9353 .9640 .8583 .9001 .7831 FACTOR 4 NA .3747 S04 .3548 BR .3328 SI .2605 LI .2527 CL .1460 CS .1303 RB .0864 B .0811 K .0408 PH .0316 TDS .0300 CA -.0900 MG -.1358 I -.1897 SR -.1941 Aik -.2765 190 TABLE A-5 (Continued) Case 1 (continued) B) VARIMAX Rotation FACTOR 1_______FACTOR 2_______FACTOR 3_______ FACTOR 4 B .9063 CL .9271 NA .7551 SI .8366 LI .8919 TDS .8160 S04 .5831 CS .3545 RB .8682 MG .6562 PH .1753 BR .2545 K .8496 CA .4251 CL .1273 RB .2399 BR .8232 I .3988 LI .0946 I .2087 CS .8054 SR .3930 TDS .0222 CA .0942 CA .7808 BR .2762 BR -.0087 MG .0917 SR .7117 K .2704 Aik -.0220 SR .0554 MG .5555 RB .2341 SI -.1986 B -.0109 I .5118 NA .2176 B -.1986 TDS -.0252 CL .2611 LI .1591 I -.2789 CL -.0552 SI .1999 B .0177 CS -.2988 LI -.1685 TDS .1136 SI -.0606 SR -.3062 S04 -.1768 Aik -.0007 CS -.1233 K -.3369 I -.2039 PH -.0360 ALk -.4355 MG -.3814 NA -.2519 S04 -.2465 S04 -.5736 CA -.4059 PH -.2576 NA -.5465 PH -.6475 SR -.4858 Aik -.5892 C) PROMAX Rotation FACTOR 1 FACTOR 2 RB .9455 CL .9548 K .9362 TDS .8225 B .9113 MG .7484 CA .8988 CA .5568 LI .8686 SR .5174 BR .8666 I .4858 SR .8353 K .4117 CS .8287 BR .4010 MG .7168 RB .3775 I .5939 LI .2954 CL .3936 B .1677 SI .2700 NA .1028 TDS .2484 CS .0139 Aik -.1141 SI -.0266 PH -.1918 Aik -.4251 S04 -.4377 S04 -.6249 NA -.6208 PH -.6493 FACTOR 3 NA .9182 S04 .7093 PH .2914 Aik .1577 CL -.0648 TDS -.0974 LI -.2366 BR -.4100 I -.4372 SI -.4390 B -.5231 MG -.6377 CS -.6451 RB -.6843 K -.7008 CA -.7245 SR -.7659 FACTOR 4 SI .8684 CS .4515 RB .3245 BR .2998 K .2939 CA .1749 SR .1422 MG .1404 B .0784 TDS -.0626 CL -.0991 LI -.1190 I -.1531 S04 -.2288 PH -.2428 NA -.3874 Aik -.5571 191 TABLE A-5 (Coi -ined) Case 1-b) Sane as case 1 except all samples are used. 1 Factor Eigenvalue Difference Proportion Cumulative 9.1174 6.5968 0.5960 0.5960 COMMUNALITIES .5176 PH Aik .5372 MG .8931 RB .9598 TDS .6799 TOTAL 13.832 BR I NA CS 2 2.5206 1.0681 0.1648 0.7608 .8189 .5404 .9797 .8788 A) PRICXPAL FACTORS FACTOR 1_______FACTOR 2 CA .9761 PH .5126 K .9636 CS .4976 RB .9582 B .3463 SR .9279 ALK .3335 MG .8810 S04 .3018 BR .8353 SI .2571 B .8118 RB .1848 CS .7759 K .1476 LI .7254 LI .1405 I .6451 BR .0760 CL .5455 CA -.0171 TDS .4224 SR -.0022 SI .3652 I -.1473 ALK -.2862 MG -.3128 PH -.4126 NA -.5646 NA TDS -.7060 -.6708 S04 -.6839 CL -.7767 CL K S04 B 3 1.4524 0.7109 0.0949 0.8557 4 0.7414 0.2658 0.0485 0.9042 .9469 .9520 .7611 .8605 CA LI SR SI .9641 .8583 .9000 .7831 FACTOR 3_______ FACTOR 4 ALK .5173 NA .3747 LI .4984 S04 .3548 PH .2892 BR .3329 S04 .2765 SI .2605 B .2737 LI .2528 NA .2655 CL .1460 I .2580 CS .1303 CL .1573 RB .0864 BR .0678 B .0811 CA .0539 K .0408 TDS .0455 PH .0316 SR .0366 TDS .0300 K .0075 ALK -.0900 RB -.0014 MG -.1358 MG -.0249 I -.1897 CS -.1103 SR -.1941 SI -.7181 HC03 -.2765 5 4757 6457 0311 9353 192 TABLE A-5 (Continued) Case lb (continued) B) VARIMAX Rotation FACTOR 1 FACTOR 2 B .9063 CL .9271 LI .8919 TDS .8160 RB .8682 MG .6562 K .8496 CA .4251 BR .8233 I .3988 CS .8054 SR .3930 CA .7808 BR .2762 SR .7117 K .2704 MG .5555 NA .2176 I .5118 RB .2341 CL .2612 LI .1591 SI .1999 B .0177 TDS .1136 SI -.0606 ALK -.0008 CS -.1233 PH -.0360 ALK -.4355 S04 -.2465 S04 -.5736 NA -.54654 PH -.6475 FACTOR 3 NA .7552 S04 .5832 PH .1753 CL .1273 LI .0947 TDS .0222 ALK -.0221 BR -.0087 B -.1964 SI -.1986 I -.2789 CS -.2988 RB -.3062 K -.3369 MG -.3814 CA -.4059 SR -.4858 FACTOR 4 SI .8366 CS .3544 BR .2545 RB .2399 K .2087 CA .0942 MG .0917 SR .0555 B -.0109 TDS -.0252 CL -.0553 LI -.1685 S04 -.1768 I -.2039 NA -.2519 PH -.2576 ALK- .5892 C) PROMAX Rotation FACTOR 1 FACTOR 2 RB .9455 CL .9518 K .9362 TDS .8225 B .9114 MG .7484 CA .8988 CA .5568 LI .8686 SR .5174 BR .8666 I .4858 SR .8353 K .4117 CS .8287 BR .4010 MG .7168 RB .3775 I .5939 LI .2954 CL .3936 B .1677 SI .2700 NA .1028 TDS .2484 CS .0139 ALK -.1141 SI -.0266 PH -.1918 ALK -.4251 S04 -.4377 S04 -.6249 NA -.6208 PH -.6493 FACTOR 3 NA .9182 S04 .7093 PH .2914 ALK .1577 C'L -.0648 TDS -.0974 LI -.2366 BR -.4100 I -.4372 SI -.4390 B -.5231 MG -.6377 CS -.6451 RB -.6842 K -.7008 CA -.7245 SR -.7569 FACTOR 4 SI .8684 CS .4515 RB .3245 BR .2998 K .2939 CA .1749 SR .1422 MG .1405 B .0785 TDS -.0626 CL -.0991 LI -.1190 I -.1531 S04 -.2288 PH -.2428 NA -.3874 ALK -.5571 193 TABLE A-5 (Contined) Case 2) All samples are used, pH variable included TDS partialled out. Factor Eigenvalue Difference Proportion Cummlative 1 8.775 7.1462 0.6141 0.6141 COMMUNALITIES PH .3776 ALK .4500 MG .8876 RB .9579 TOTAL 12.66 BR I NA CS 2 1.6290 0.2249 0.1140 0.7281 8018 4500 9889 8727 A)PRINCIPAL FACTORS FACTOR 1_______FACTOR 2 CA .9724 ALK .5664 K .9671 LI .5240 PH RB .9652 .5240 SR .9197 S04 .3956 CS .8713 B .3156 B .8487 I .2953 MG .8484 NA .2046 BR .8236 CL .0746 .7121 BR .0624 LI I .5581 CA .0355 SI .4191 K .0308 CL .3540 RB .0296 ALK -.1447 SR .0248 PH -.2390 CS -.0345 S04 -.5985 MG -.1209 -.6408 NA -.8268 SI CL K S04 B 3 1.4041 0.5441 0.0983 0.8263 4 0.8579 0.2715 0.0602 0.8865 .8955 .9481 .6978 .8552 CA LI SR SI .9690 .8401 .8927 .7837 FACTOR 3_______ FACTOR 4 CL .8568 S04 .3980 NA .3913 BR .3343 MG .3484 NA .3320 CA .1187 SI .3303 SR .0892 LI .2394 BR .0887 CL .1742 LI .0347 CS .1644 I -.0561 RB .1085 ALK -.0799 B .0824 K -.0896 PH .0731 RB -.1166 K .0626 S04 -.1570 CA -.0900 B -.1700 MG -.1786 CS -.2919 SR -.1943 SI -.2973 I -.2177 PH -.3253 ALK -.3192 5 5884 1331 0412 9277 TABLE A-5 (Continued) Case 2 (continued) B) VARIMAX Rotation FACTOR 1_______FACTOR 2_______FACTOR 3_______ FACTOR 4 B .9165 S04 .7701 SI .8019 CL .9086 RB .9083 NA .6064 CS .3015 NA .3911 K .8949 PH .4422 BR .2732 MG .3634 LI .8627 LI .1101 RB .2166 BR .2812 CS .8511 ALK .1062 K .1871 LI .2393 .8249 CA BR -.094 0 MG .1056 CA .2027 BR .7996 B -.1159 CA .0761 SR .1376 SR .7586 SI -.1648 SR .0198 K .0482 MG .5905 CL -.1795 CL .0123 RB .0355 I .5655 CS -.2000 B -.0405 B -.0056 SI .2661 I -.2512 NA -.1577 I -.0199 CL .1935 RB -.2911 LI -.1628 S04 -.0616 PH .0426 K -.3314 S04 -.1768 ALK -.1232 ALK .0307 CA -.4947 I -.2584 CS -.1320 S04 -.2641 SR -.5452 PH SI -.3313 -.2065 NA -.6659 MG -.6289 ALK -.6501 PH -.2655 PROMAX Rotation C) : FACTOR 1 FACTOR 2 RB .9642 S04 .8334 K .9582 NA .7999 CA .9239 PH .4589 B .9124 ALK .2018 CS .8866 LI -.1582 SR .8629 CL -.2522 BR .8345 SI -.3722 LI .8158 I -.3744 MG .7365 B -.4013 I .5819 BR -.4021 SI .3455 CS -.5133 CL .2776 RB -.6059 ALK -.0508 K -.6343 PH -.0936 CA -.7447 S04 -.4381 SR -.7616 NA -.7674 MG -.8039 FACTOR 3 SI .8471 CS .4149 BR .3514 RB .3405 K .3141 MG .2230 CA .2092 SR .1558 B .0690 CL .0138 LI -.0942 I -.1661 S04 -.2887 NA -.3123 PH -.3625 ALK -.6454 FACTOR 4 CL .9082 NA .3936 MG .3615 BR .2758 LI .2589 CA .2062 SR .1432 K .0477 RB .0339 B .0075 I -.0003 S04 -.0516 ALK -.0875 CS -.1382 PH -.2448 SI -.2463 195 TABLE A-5 (Confined) Case 3) All samples are used, pH variable not included TDS partialled out 1 Factor Eigenvalue Difference Proportion Cummulative 8.7132 7.2014 0.6513 0.6413 Communalities Br .7983 I .4440 NA .9898 CS .8827 T0TAL=12.3466 CL K S04 B 1.2784 0.4353 0.0956 0.8599 4 0.8432 0.4057 0.0630 0.9229 .9755 .8138 .9097 .7611 ALK MG RB 2 1.5118 0.2333 0.1130 0.7643 .9167 .9479 .7365 .8822 A) PRINCIPAL FACTORS FACTOR 1_______FACTOR 2 .9730 CA ALK .4809 K .9696 LI .4636 RB .9663 CL .4534 SR .9209 NA .3669 CS .8729 S04 .2924 B .8508 I .2323 MG .8399 B .2119 BR BR .8219 .0918 LI .7177 CA .0740 I .5604 MG .0625 SI .4131 SR .0364 CL .3491 K -.0283 ALK -.1389 RB -.0291 S04 -.5933 CS -.1670 NA -.8271 SI -.7017 CA LI SR SI .4789 .8474 .9624 FACTOR 3_______ FACTOR 4 ALK .3747 S04 .4286 S04 .3395 BR .3327 B .3198 NA .3225 CS .2421 SI .3043 I .1858 LI .2336 LI .1711 CS .1849 RB .1449 CL .1344 K .0597 RB .1207 BR -.0592 B .1051 SI -.0742 K .0579 CA -.1139 CA -.1011 SR -.1216 MG -.1769 NA -.2588 I -.2035 MG -.3261 SR -.2132 CL -.7557 ALK -.2966 5 4375 0403 0327 9556 196 TABLE A-5 (Continued) Case 3 (continued) B) VARIMAX Rotation FACTOR 1_______FACTOR 2_______ FACTOR 3_______FACTOR 4 B .9077 SR .6731 SI .7988 CL .9314 RB .8650 MG .6473 CS .3057 MG .3877 LI .8531 CA BR .6035 .2685 NA .3441 K .8249 K .4648 RB .2237 BR .2782 CS .8238 RB .4016 K .2089 CA .2517 BR .7863 I .3421 MG .1179 LI .2413 CA .7328 CS .3086 CA .1042 SR .2097 SR .6386 B .2338 SR .0687 K .0867 I .5180 SI .2001 CL .0237 RB .0524 MG .5137 BR .1747 B -.0576 I .0044 SI .2288 CL .1513 LI -.1631 B -.0150 CL .1604 LI .0341 NA -.1858 CS -.1236 ALK .0543 ALK -.0757 S04 -.2227 S04 -.1349 S04 -.1269 NA -.7202 I -.2421 ALK -.1448 NA -.5641 S04 -.8078 ALK -.6703 SI -.1748 C) PROMAX Rotation FACTOR 1 FACTOR 2 RB .9600 SR .8671 K .9411 CA .8454 B .9247 MG .8176 CA .8967 K .7609 CS .8876 RB .7179 BR .8422 CS .6231 LI .8276 B .5251 SR .8204 BR .5028 MG .7120 I .4534 I .5703 SI .3584 SI .3271 LI .3184 CL .2699 CL .2514 ALK -.0366 ALK -.1786 S04 -.3779 S04 -.8324 NA -.7293 NA -.8741 FACTOR 3 SI .8506 CS .4594 RB .3913 K .3806 BR .3775 CA .2814 MG .2676 SR .2482 B .0975 CL .0245 LI -.0571 I -.1153 S04 -.3594 NA -.3869 ALK -.6538 FACTOR 4 CL .9388 MG .4203 NA .3089 BR .3052 CA .2948 LI .2907 SR .2519 K .1259 RB .0914 I .0498 B .0369 CS -.0926 ALK -.1086 S04 -.1480 SI -.2004 197 TABLE A-5 (Contined) Case 4) All samples are used, pH variable not included TDS not partialled out. Eigenvalue £ Difference K? Z Proportion A 4 Cummlative 6 Communality BR .8152 I .5377 NA .9814 B 8.9521 2.2999 1.3506 0.7291 6.6522 0.9493 0.6215 0.3075 0.6246 0.1605 0.0942 0.0509 0.6246 0.7850 0.8793 0.9302 CL 9594 K 9536 S04 7765 .8768 SI CA .9676 LI .8355 RB .9617 .7595 TDS ALK .5646 MG .8722 CS .8864 .6761 : 9085 TOTAL=13.33 A) PRINCIPAL FACTORS FACTOR 1_______FACTOR 2_______ FACTOR 3_______ FACTOR 4 CA .9773 CL .8135 ALK .5786 NA .3694 K .9694 TDS .7152 LI .4831 S04 .3642 RB .9626 NA .5824 S04 .3321 BR .3308 SR .9308 MG .3144 B .3227 SI .2474 MG .8675 I .1990 • I .2198 LI .2416 BR .8359 CA .0554 NA .2004 CS .1422 B .8209 SR .0502 BR .0687 CL .1355 CS .7873 LI -.0458 CL .0416 RB .0923 LI .7359 BR -.0474 CA .0280 B .0864 I .6439 K -.1117 RB .0124 K .0384 CL .5268 RB -.1623 K .0001 TDS .0225 TDS .4023 S04 -.2856 SR -.0047 CA -.0932 SI .3630 ALK -.2860 TDS -.0479 MG -.1311 ALK -.2722 B -.3020 CS -.0512 I -.1877 S04 -.6723 SI -.3194 MG -.0599 SR -.1987 NA -.6824 CS -.4935 SI -.6808 ALK -.2717 198 TABLE A-5 (Continued) Case 4 (continued) B) VARIMAX Rotation FACTOR 1_______ FACTOR 2_______FACTOR 3_______ FACTOR 4 B .9037 CL .9546 NA .7449 SI .8107 LI .8695 TDS .8119 S04 .6721 CS .3237 RB .8498 MG .5947 ALK .0331 BR .2588 K .8158 I .4009 LI .0039 RB .2435 BR .8151 CA .3943 CL -.0177 K .2263 CS .8098 SR .3662 BR -.0889 MG .1344 CA .7348 NA .3213 TDS -.0933 CA .1269 SR .6512 BR .2753 SI -.1961 SR .1008 MG .5167 K .2446 B -.2414 TDS .0493 I .4687 LI .2314 CS -.3119 CL .0342 CL .2161 RB .1984 I -.3604 B -.0415 SI .2043 B .0144 RB -.3753 LI -.1610 TDS .0759 SI -.1453 K -.4208 I -.1659 ALK .0144 CS -.1689 MG -.4832 NA -.2208 S04 -.1854 ALK -.3370 CA -.5062 S04 -.2341 NA -.5240 S04 -.4854 SR -.5832 ALK -.6431 C) PROMAX Rotation FACTOR 1 FACTOR 2 RB .9478 CL .9709 K .9299 TDS .8183 B MG .9201 .6632 CA .8833 .4870 CA BR .8619 I .4632 LI .8549 SR .4544 CS .8502 BR .3573 SR .8133 K .3417 MG .6976 LI .3188 I .5717 RB .2971 CL .3506 NA .2356 SI .2877 B .1164 TDS .2129 CS -.0755 ALK -.1036 SI -.1226 S04 -.4126 ALK -.3788 NA S04 -.5286 -.6382 FACTOR 3 NA .8789 S04 .7738 ALK .2075 TDS -.2172 CL -.2204 LI -.3395 SI -.4145 BR -.4956 I -.5172 B -.5704 CS -.6528 MG -.7322 RB -.7497 K -.7777 CA -.8158 SR -.8411 FACTOR 4 SI .8522 CS .4534 RB .3707 K .3541 BR .3406 CA .2523 SR .2292 MG .2245 B .0863 TDS .0326 CL .0161 LI -.0772 I -.0833 S04 -.3174 NA -.3861 ALK -.6186 199 Figure A 7 . R - m o d e f a c t o r a n a l y s i s r e s u l t s , c a s e 1. O n l y s a m p l e s w ith pH v a r i a b l e are used, pH v a r i a b l e I n c l u d e d , TDS n ot p a r t i a l l e d out. Ca, K, Rb, Sr Mg.Br.B Cs,U Cs b i ,a l k ,s o 4 Na,S04,Br SI,U SI pH,S04lB,Na Rb,K,U Br 1 CI.Cs.Rb K,pH,TDS,B Rb,Mg Cs Mg.I.Sr Sr.Ca Na,S04 TDS,Cl proportion OP VAR IAHCE 9.5J 16. 51 59. 61 CASE 1 - PRINCIPAL Figure A-7 COMPONENTS 4. 9Z 200 Cl Br.Ca.TDS.Sr.K 201 CASE 1 - VARIMAX ROTATION B U .R b.K .B r.C s CI.TDS SI Ca.Sr - - - - Na — ------- - Mg Mg.i S 04 C a.I.Sr Cl,SI “■ TDS - - Br,K ,R b,N a - - pH ,C l ------- U ,B C s.B r l,R b - II,TDS A LK .pH - so4 B r.A LK Cs C a.M g.S r ------- - SI,B _ C s.S r.K .I ALK - - ALK pH 1 1 _ 4 3 Cl TDS Na Mg so4 SI C a .S r l,K ,B r,R b Cl S I,T D S — 2 R b .K .B C a .U .B r .S r C s ,M g - Ca,Sr,M g so„ Na B,TDS,Cl U ,S 0 4 ,l Na.pH Cs U — - B ,N a pH — R b ,B i,K _ _ C a .S r ,M g ' ALK Cs ALK pH - B SI _ T D S .C l U ,l,p H ,S 0 4 C l,T D S _ - ~ - - - U S04 Na ALK B r.I.S I B S 0 4 ,pH M g ,C s ,R b Na ALK K .C a Sr CASE 1 - PROMAX R O T A T I O N Figure A-7 202 Figure A-8 . R - m o d e f a c t o r a n a l y s i s r e s u l t s , c as e 2. samples are used, pH variable included, partialled o u t . All TDS 3 2 1 4 Cl Ca.K.Rb.Sr C$,8,Mg,8r U ALK,U,pH 1 so4 Si Cl Mg.Na B.l Na U Cs Mg pH - LALK.K Rb,S04,B - --- « Cs.SI pH so4 203 Ca Sr,Br,U CI,Br,Ca,K Rb.Sr ALK S04,Br,Na SI CI.Cs Rb,B,pH,K Ca Mg.Sr.l ALK SI Na P R O P O S T IO N OF V A R IA N C E 1 U 4 I 9 .8 1 01.** CASE 2 - P R IN CI PAL Figure A-8 I C O MP ON E N T S 204 CASE 2 - VAR1MAX ROTATION 1 2 3 B Cl SI B b .U .K .C a B f .C a Sr 4 m * S04 * ““ “ — - Na I.M g pH M g .N a .B r SI C t.B r - - «. - _ K .R b M g .C a S r .C I U ALK A L K ,p H B ,S I so4 - K .B b B B t .C I - U C s .S r « - Cl B. 1 C s .S O ^ .A L K U ,N a K .R b C s .l _ _ - - s o 4,i - PH pH Ca Sr Na ALK Mg - ---------- - 1 - - 2 S 0 4 .N a - - 3 B b .K .C a .B C s .S r . B r . U Mg - — 4 Cl SI - — - - — - 1 SI - N a .M g B r .U Cs PH Cl B r .R b .K - ~ - - ALK Mg C a .S r - - B .C I U A K .p H - - _ Cl S l.l U .l - - 1,S O , , A L K Cs - - so4 so4 Ca Sr K .R b .B p H ,S I N a .p H ___ E L ! l _ R b .K _ - - _ _ C a .S r Mg Na CASE _ ALK 2 - PROMAX R O T A T I O N Figure A--8 _ - 205 F i g u r e A - 9 . R - m o d e f a c t o r a n a l y s i s r e s u l t s , c a s e 3. s a m pl es are used, pH v a r i a b l e not i n c l u d e d , p a r t i a l l e d out. All TDS C a .K .B b .s r C »,B ,M g ,B r AUCU .C I A L K ,S 0 4,B Br.Na.SI N a ,S 0 4 C s.C l.R b.B 206 l,B Br.Ca.Mg.Sr K ,R D p r o p o r t io n of 65. 12 11.3: C a .S r Ca.Mg 9 .6 £ 6.3£ v a r ia n c e CASE 3 - PRINCIPAL COMPONENTS Figure A-9 207 CASE 1 3 - VAR1MAX 2 ROTATION 3 e R b .U .K .C * B r.C a 4 Cl SI Sr S r . M g .C a ________ i , M g _ _ --------- ---------- K ,R b C a ,l SI Cl ALK so4 B .S I C n .B r B r .C I U K .R b M g .C a S r.C I ALK B ■“ ““ M g .N a . B r C a ,K J ,S r — K ,R b ,t B C s .S O ^ .A L K U .N a S 0 4 ,l ---------- ---------- Na — Na ALK s. M — - so 4 2 1 3 R b ,K ,B ,C a C s ,B r ,U ,S r S r ('C a ,M g Mg Rb Cs I B ,B r SI 1 S I ,U 4 SI Cl C s .R b .K .B r Mg N a ,B r , C a ,U K C a .M g .S r Cl Sr Cl ALK ALK B ,C I K .R b LB U 1 C s .A L K so4 £» s SI 1 1 I1 1 1 1 S O jj.tla Na - - --- ALK - S 0 4 ,N a CASE 3 - PROMAX R OTATION Figure A - 9 - _ - 208 Figure A-10. R - m o d e f a c t o r a n a l y s i s r e s u l t s , c a s e A. s a m p l e s are u s e d , p H v a r i a b l e n ot i n c l u d e d , not p a r t i a l l e d out. All TDS Rb.K.B Ca,U,Br,Sr Cs.Mg - m «M 2 3 Cl TDS Na - so4 - SI - m Mg Ca.Sr 1 l,K,Br,Rb U pH Cs Rb.Br.K Cl SI,TDS - - Ca.Sr,Mg B,Na Cs B Cl,TDS TDS,Cl U.l SI . pH,S04 PH U - so4 ALK Na S 04,pH Br.I.Sl B ____ Mg.Cs.Rb K.Ca Sr — “ CASE 4 - PRINCIPAL COMPONENTS Figure A-1Q Na ALK 209 ALK ALK 210 CASE A - VAR1MAX ROTATION 1 2 3 4 Cl TOS SI «z U.Rb^Br.Cs Ca “ Cl,SI l,Ca,Na “ - Br - -- ALK LI K,LI,Rb t d s .a l k B so4 ---- Na,S04 - K,Mg so4 Ca Sr Na 1 2 Rb.K.B,Cs Ca,Br,U,Sr - B U,1 — ALK Cs,Br,Rb,K Mg,Ca.Sr TDS,Cl Br.TDS.CI SI.B Cs.I.Rb SI.Cs - ------- 1 1 1 1 1 _____ M g ____ 1 I Sr Mg ALK 3 4 Na Cl,TDS SI so4 Mg,I Mg Cl,SI - TDS ------- Ca.Sr,1 - “ Rr.K LI,fib Na Cs - -- - Ll,l SI TDS.CI.LI ---- - ---- - ALK - -- S 0 4,Na Si.Bf 1 so4 Na so4 -- Aik B Cs Mg.Rb.K Ca.Sr CASE - B,TDS,Cl ALK B Cs ALK nb,K,Br Ca.Sr,Mg A - PROHAX Figure A-10 ROTATION - - 211 EFFECT OF pH VARIABLE Figures A-7 and A-10 shows the effect of including pH in the data set on factor makeup when TDS is partialled out. No significant changes in the makeup of the 4 factors occurs with the varimax rotation when pH is not included. Likewise, no significant changes are observed in the promax rotation, although slight changes in the loadings of Ca, Mg, and Sr in factor 2 occur when pH is removed. In both rotations, pH loads in the factors near ALK and S04 . Removing pH also does not change the results when TDS is partialled out (compare Figure A-7 and A-1 0) . However, factor 2 is found to invert upon removal of pH, although the relative factor loadings of the variables remains constant. Also, including pH apparently reduces the loading of Ca, Mg, and Sr in factor 3, but the relative positioning of these elements remains constant. significantly alter the In sum, factor pH apparently does not makeup or relative factor loadings. EFFECT OF PARTIALLING OUT SALINITY As discussed above, variations in sample salinity may mask identification of other processes affecting the brine chemistry. TDS In order to remove the influence, variable) correlation is partialled matrix in the out R-mode by using brine salinity, (except S04 and therefore, a calculations. important to determine the effect of salinity, because most elements salinity (the partial It is for example, and Na) increase with the variables may intercorrelate 212 with salinity in this respect. The R-mode analysis results preformed with and without TDS partialled out, are compared A -8 and A-9, respectively. in Figures A-7 and A-10, and The most apparent change resulting from partially out of salinity is found in the relative makeup and importance of factors 2, 3, and 4: Factor______________ 1__________2__________ 3__________ 4 % variance with 59.6 TDS not partialled out 16.5 9.5 4.9 % variance with TDS partialled out 11.4 9.8 6.0 61.4 While the amount of variance explained by each factor does not dramatically change the partialling out of salinity affects the factors switch TDS. Factors make-up of factors 2 to in their importance that might represent 4. In upon essence, partially water-rock the out of interactions (factor 2 and 3) increase in their relative importance over a factor that might represent salinity (factor 4) . EFFECT OF ROTATION METHOD Both study. varimax and promax rotations Varimax is an orthogonal an oblique rotation method. were rotation, used in this while promax In the varimax solution, is factor axes are kept orthogonal during rotation until the best fit is obtained, maximizing the variance each factor explains 213 (Hitchon et a l ., 1971). Promax differs in that the axes are not constrained to be orthogonal. Comparing the results of the cases demonstrates that the rotation method chosen, for this the example, factors. generally However, separated using result was does the the not alter variables promax the makeup appear oblique to be rotation. found by Long et a l . (1986) A of better similar and Hitchon et a l . (1971) . A problem with oblique rotation methods is the possible correlation between uncorrelated factors, which 1986). When (Davis, by design, factors correlate, relationships between the variables and the highly complex, remain hidden. factor and the true occurred using or if pH was included). clear, be the factors may be controlling processes may A correlation between the first and second the regardless of the test case not should but the promax rotation (r = -.53), (if salinity was partialled out The meaning of this correlation is observation that both orthogonal and oblique rotations produce nearly identical factors suggests that factor correlation does not effect factor makeup. INTERPRETATION OP R-MODE RESULTS The varimax and promax rotations with salinity partialled out and pH not included (case 2, Figure A-9) best illustrate the factor interpretations Factor loadings can be analysis made between results, from — 0.25 each were although similar case presented. not considered significant when making the interpretations. 214 Factor 1 is characterized loadings on B, Rb, highly negative common source elements, It is other loading of factor, but seawater Na. eg., It a very Na loads is this may source as for a the such as Rb and B. strongly reflect evaporation. positive interpreted seawater so high Sr, Mg, and I, and a for minor elements clear why elements, during Li, K, Cs, Br, Ca, especially not by inverse the to behavior Alternatively, the of the Na inverse relationship between Na and Cl in this factor may represent halite equilibrium. This first factor Hitchon et a l . (1971) loadings on minor earth elements. salinity factor as to the first factor (Figure A-5) , as both have high alkaline metals, and of (+) alkaline The negative loading of Na in factor 1 with Egleson and Querio mode similar elements, partialled minor elements is out is (1969) also similar interpreted to the each high study. loading of (B, K, Li, I, B r , and N H 3) in their first Rshowing a common mechanism affecting these elements. Factor 2 is characterized by high Mg, and Ca, and high negative interpreted perhaps intermediate as also characteristic loadings representing indicating of this different trials studied, S04 . (+) (+) loadings on Sr, loadings on K, Rb, Na a CaS04 factor, and S04 . carbonate mineral found This I, and Cs, factor mineral factor, equilibrium. in each is of A the is the strong co-loading of Na and A possible explanation is that this loading represents 215 the decrease in Na in evapo-concentrating seawater halite precipitation) samples contain are possible and the fact that more highly saline little or include: (1) no S04 . Other explanations that CaS04 and NaCl equilibrium, both common minerals in the basin, or al. and (3) (2) NaS04 mineral dissolution, strong Na~S04 ion pairing (1971). the (due to suggested by Hitchon et NaS04 minerals have not been reported in basin, ion-pairing theoretical explanation considerations. is Pitzer not (1973) supported reports by that single ion electrolyte interaction parameters between Na and S04 are quite small, thus ion-pairing between these components is not expected to be significant. Factor 3 is single ion, Si, B r , and factor a might Carpenter (-) represent (+) loading on a loading on alkalinity. silicate-carbonate This buffering or in essence, the balance between aluminosilicate carbonate represent high intermediate (+) loadings on Cs, Rb, K, and significant equilibrium, and characterized by mineral the reactions. illite-carbonate (1978): 2K+ + CaC03 + Such a processes reactions might suggested 3Al2Si20 5 (OH)4 + by 4Si02 Ca2+ + 2KA12 (AlSi3 )O10 (OH) 2 + H 20 + C02 alkalinity) . = This is further supported by the positive loadings of K and Rb in this factor, particularly in the promax rotation. Factor 4 loading on C l , Li, Ca, loading. and Sr, This is characterized by a single high positive and intermediate (+)loadings on Na, Mg, Br, and no variable showing a strong negative is interpreted to be a salinity factor, or 216 alternatively, because a similar factor is found when TDS is partialled out, it might represent that Cl is the dominant anion in the brine samples. DISCUSSION The R-mode results appear interpretations made using graphical techniques in Chapter 1 and consistent with and chemical modeling Chapter 2. Most important, factor analysis supports a seawater origin for the Michigan basin brine, as a common source is suggested for many of the elements, especially the minor elements. because once the minor elements, enriched by evaporation, significantly reduce This is reasonable such as Br, very few B and Rb, reactions their concentrations. Q-mode suggest that this characteristic, and origin, throughout the entire Furthermore, the differences between (Berea, Traverse, Student's the and River-Niagara/Salina represent the Michigan upper Dundee) basin t-test will results reflected sample population. results suggesting Devonian formation and Richfield-Detroit the samples, might different is are degrees be of in waters interpreted to evapo-concentration reached by these waters in the basin. The importance of carbonate reactions (Chapter 1) may be supported by the combined loading of Ca-Mg-Sr in a single factor. The third factor which is interpreted to represent silicate-alkalinity buffering, tenuous, consistent is also affecting K (Chapter 1). although with somewhat proposed more reactions 217 One notable difference lack of a halogen from previous factor where Br,I , and Cl (Hitchon et al., 1971; Egleson and Querio, 1969). studies is the load together 1969; and Kramer, It is not apparent why this factor is not found, but it may reflect that the I enrichment occurs by processes not related to evapo-concentration, such as from organic matter decomposition (Egleson and Querio, 1969). CONCLUSIONS (1) Michigan Q-mode factor basin brine homogeneous analysis data population, demonstrates are described interpreted as a salinity gradient. that the characteristic of by factor a single a R-mode factor analysis of the entire data set is therefore, justified. (2) R-mode factor analysis was orthogonal and promax oblique rotation trial determine, cases to including pH resulting similar and factor the interpretations was out what of varimax the effect salinity evaluated. can be made using methods. Different for example, partialling makeup, run In from all on of the generally, cases. Four factors were found to account for 90 to 92% of the variance in the data. Communal it ies were high (>.75) for most variables. (3) The factors are interpreted as follows: Factor 1: minor elements, common source for suggested to be most elements including a seawater source. Factor 2: A carbonate-sulfate mineral factor. Factor 3: Silicate-carbonate buffering or equilibrium. 218 Factor 4: A salinity (4) The interpretations results, and multivariate made suggest rock reactions. or dominant anion (Cl) factor. from statistical graphical and methods chemical support modeling a seawater origin modified by water- the APPENDIX B APPENDIX B METHODS BRINE SAMPLING The brine samples directly from several Niagara/Salina distribution each site, the used lines well or in head this whenever samples the bottom stand and were collected possible, although were of collected separator from tanks. At sampling valves at the well head were opened and the brine-hydrocarbon mixture was pre-rinsed, study plastic separate carboy. for The collected mixture several minutes, brine was withdrawn through the bottom in a was 5 gallon allowed after which spigot. to clean The brine was passed through glass-fiber w o o l , filtered through Watnum #1 filter paper, and collected in a plastic beaker. Some samples would not separate in-field because of hydrocarbon viscosity and in these instances, brine mix was collected in the combined hydrocarbon- sealed plastic bottles and allowed to separate in the laboratory over several days to several weeks. the bottle and The brine was withdrawn from the bottom of filtered in the same manner as above. The following splits were taken from each sample: 1) 25ml were pipeted in to a capped widemouth plastic bottle for pH, Eh, and alkalinity analysis. 2) 125ml were carefully pipeted into plastic containing 125ml of 5% HN03 acid for cation analysis. 219 bottles 220 3) 125ml were preserved with 1ml of reagent grade formaldehyde for S04 analysis. 4) 500ml were collected in boro-silicate glass bottles with teflon sealed caps for stable isotope analysis. it was necessary to open these bottles to Often release accumulating gas pressure. 5) 500ml analysis. case for observed were collected for Cl and If salt precipitation was Niagara/Salina in the replaced by brines, filtered diluting 125ml or brine, of strontium expected, if salt then brine as was crystals this with isotope the were sample 12 5ml of was double distilled H 20. The field dilutions were made using a single 100ml and 25ml Class A glass volumetric pipets. set of All samples collected for chemical analysis were stored in high density polyethelyne bottles. The samples were labeled and transported to the laboratory in a covered plastic pail that was iced on particularly warm days. FIELD ANALYSIS Field analysis consisted of measuring temperature, Eh, and when measured possible, using a alkalinity. standard Temperature laboratory pH was measured using an Orion model Orion 91-05 Standardization reference gel of standards temperature of the filled pH electrode of pH 4 was and was thermometer. 407 pH meter with an combination the brine mercury (°C) pH, 7. normally was pH made Because between electrode. using well 9 to NBS head 10°C, 221 the pH standards were chilled on ice during the summer field work. Electrodes detergent. were An cleaned Orion model between use with Alconox 96-78 combination platinum electrode was used for measuring Eh, which was normally done concurrent with pH. Alkalinity was measured following the procedure in Brown et al. with H 2S04 standardized buret. (1970) by titrating 25.0ml samples acid delivered from a 50ml glass The acid was standardized daily using a standardized HC03 solution. DISCUSSION There between Most are several sampling brine importantly in and is the temperature that occurs brine aspects Michigan normal differ considerably salinity groundwater. potential change during is that brine produced in pressure- production. from depths Because of several thousand feet of depth, brine undergoes considerable changes in temperature changes result precipitation and in of pressure the salts during exsolution and production. of paraffin in gases the These and in well the bore, a common problem faced during Michigan oil production. There is no these method for surface sampling that will reduce changes, short of using down-hole pressurized samplers. chemical changes temperature changes in brines that are difficult well understood at this time. result from to evaluate The pressure- and are not Several aspects of the deserve some measurements also measurements involve the use of pH Eh, and discussion, alkalinity because electrodes. these Sources of error that become significant in using electrodes to measure high salinity waters include the changes in liquid junction potentials caused composition of by the differences standards specificity of electrodes. and in samples, salinity and the and non­ Liquid junction potential errors could be minimized if standards had compositions that match the brines, which is not possible for highly saline brines such as the Michigan basin brines. standards suggested by For example, the TRISH+ Millero (1979) for seawater have a salinity some 9 to 10 times average Michigan brines. The commercial measuring less than the standards used in this study were dilute solutions, therefore, liquid junction error may have been a significant error in this study. electrodes may also respond to monovalent ions and Li when present at high concentrations Similar problems affect electrodes responding Kharaka a l ., were not et stable to 1980) . over Eh Fe measurements Often the short and pH long (Levine, as or S species and such as Na 1978). w e l l , with Eh (Langmuir, 1971; Eh measurements periods of time, could be arbitrary adjusted by slowly stirring the Considering these problems, pH or sample. the pH and Eh measurements are probably not representative of true solution conditions, and the true pH-Eh values of the brines at subsurface conditions remain an unknown at this time. 223 It was also observed during the alkalinity titrations that the pH would not respond to the addition of acid, upon the addition of very large amounts of acid. even This was observed most often in the more highly concentrated Detroit River, This Richfield, pH response and may phenomenon described measurement may acids present 1975). Niagara/Salina be due, in above, formation part, however, have been affected by in the brine ( Case, 1945; Attempts at to measuring the samples. the the electrode alkalinity dissolved Willey dissolved organic et a l ., organic acid content of these brines using liquid-ion-chromatography were not successful due to salinity interferences personal communication). However, For example, preformed on titration a near carbonate is thought buffered, and a pH of 3.5, not to reflect the near the a non-saline inflection points are observed observed in the ground water sample. PH samples, Assuming that the pH measurements accurate in the brines, brines and Niagara/Salina typical groundwater sample. these in the brines was Figure B-l shows alkalinity titrations Richfield of Fischer, evidence suggesting that dissolved organic acids might be present found. (B. pH of are for 4.5 An inflection at this presence of acetate, a principal organic acid in brines (Willey et a l ., 1975). ANALYTIC METHODS Cations were measured using emission spectroscopy methods, instrument. Anion atomic adsorption and on a Perkin-Elmer 506 A.A.S. analysis was by titrimetric, 224 pH I 2 3 4 5 6 7 6 9 ml of a c i d F i g u r e B - l . Alk al in i t y ti tr at i o n curves, pH v e . v o l u m e of added (ml). Curve A, Ri c hf i e l d brine s am pl e, curve B, a N i a g a r a / S a l i n a f o r m a ti o n b ri n e , curve C, a n e a r - s u r f a c e ground water from Michigan . ecid 225 colorimetric, and gravimetric methods. Individual procedures and their references are listed in Table B-l, and selected methods are discussed in detail here. Sample Preparation Suitable working dilutions were prepared based on the concentrations of species of interest. and K analysis, pipeted 1ml For Ca, Mg, Sr, Na, a 1:2000 dilution was prepared by carefully of the volumetric flask, 50% field dilution diluted a 1000ml adding 1ml of concentrated HN03 , and then bringing the volume up with de-ionized, field into samples were hydrocarbons, aliquots of found distilled water. to contain If visible of non-diluted brine were withdrawn from the bottom the sample filtered, and allowed to sit. bottles in the laboratory, This procedure was repeated until clean brine was obtained, which was then handled in a similar described abo v e . fashion to the Class A pipet samples (1.0ml) and volumetric flask A (11) single were used for all samples in order to minimize error between samples caused by glassware. introduces Although considerable such error in a large the analysis discussion below), this dilution was necessary bring concentrations minimize matrix analysis. All polyethylene followed for and within other diluted plastic other measurable bottles. dilutions were stored Similar in in this (see in order to ranges interferences samples dilution and the in A.A . S . pre-rinsed procedures study. to were Working standards for most components were prepared from commercial 226 TABLE B-l Components measured and analytic methods. COMPONENT PH Ca, Mg, Sr Na, K Rb, Cs Li. Cl Br I B Si n h 4n S04 Alkalinity Density TDS METHOD electrometric flame emmision w/1:10 of 87g/l LaCl ^ flame emmision w/1:10 of 25.4g/l NaCl or KCl flame emmision w/1:10 of 25.4g/l Na-K-Cl flame emmision w/1:10 of 25.4g/l Na-K-Cl Mohr titration colorimetric bromide oxidation colorimetric w/carminic acid colorimetric following extraction potentiometric titration gravimetric potentiometric titration pyconometer @2 5°C and by calculation SPG=log TDS * 7.102x10 -7 calculation DILUTION none 1:2000 REFERENCE 1 1 1:2000 1:26 1:200 none 1 :40 1 :2 1 :10 1 2 1 1 1:200 1:2 none none none 4 5 1 5 + 0.996 References: 1: Brown et al., (1979) Methods for Determination of Inorganic Substances in Water and Fluvial Sediments. U.S.G.S. Water Resources Investigation Book 5, Chapter A-l, Washington, D.C. 2: Presely, B.J. (1971), Part I: Determination of selected minor and major inorganic constituents, in: Ewing, J.I. and others, Initial Report of the Deep Sea Drilling Project, Volume VII, Part 2: Washington, D.C., U.S. Govt. Printing Office, p. 1749-1755. 3: Schrink, D.R., (1965) Determination of silica in sea water using solvent extraction, Anal. Chem., 37, 764-765. 4: Collins, A.G., Cassaggno, J.L., and Macy, V.W. (1969) Potentiometric determination of ammonium nitrogen in oil-field brines, Environmental Science and Technology, 3, 274-275. 5: A.P.I. (1968) Recommended Practice for Analysis of Oil-field Waters, American Petroleum Institute, Washington, D.C., 2nd edition, 58p.. 227 1000mg/l stock standards. Br, and Stock standards of Rb, Cs, B, I, S04 , were prepared from reagent grade salts that were oven-dried overnight and cooled in a desiccator before weighing. All standards were made in reagent grade Na-K-Cl solutions having Cl concentrations similar to the diluted sample. Ca, Mg, and Sr The alkaline earth elements were measured on a single aliquot of the ionization, 1ml sample and analysis, 1:2000 of 87g/l standard. following dilution. In LaCl2 was Flame added emission Brown et al. order to was to suppress 10ml each used for of the (1970). Na, and K The alkali dilution. 25.4 metals were also In order to reduce measured on the ionization effects, 1:2000 1 ml of g/1 NaCl or KCl was added to each 10ml of sample and standard for K and Na analysis, respectively. A red filter was used for K analysis, analysis, following and flame Brown et al. emission was used for (1970). Rb, Cs, and Li These metals were particularly difficult to analyze due to their low concentrations compared with the alkali metals. For Rb and Cs, 3ml of the 50% field diluted diluted with 10ml of distilled water, while sample were Li was measured 228 in a 1:100 dilution of the was not added to these field diluted samples, but sample. was Na-K-Cl added to the standards by adding 1 to 2ml of 25.4 g/1 Na-K-Cl solution to each 10ml against of standard. distilled measurable Rb, The water Cs, Na-K-Cl and was solution found checked to contain not or Li at the dilutions used. was by flame emission using a red filter, et al. was Analysis following Brown Schrink (1965) (1970). Silica Silica was measured by the method and Collins (1975). mixed ammonium in The method involves adding molybdate sulfuric acid 52g/l ammonium-molybdate mixed with 1ml of a solution 50ml of (100ml of 1 molar H2S04 ) to 50ml of 1:100 dilution of the field diluted sample. The mixture is stirred well and allowed to stand for 20 minutes. 15ml of 1:1 H 2S0 4 acid is then added and the mixture cooled to room temperature for several minutes on ice. 100ml pre-rinsed separatory funnel (pre-rinse and the sample-reagent In a ethyl- 1 0 .0ml of ethyl-acetate acetate and wash dox^n with acetone) is pipeted with is mixture is added. The funnel is shaken vigorously for 1 minute, and the mixture is allowed to separated. The ester phase is measured at 1 minute or aqueous phase then collected in a separate a for wavelength of is until cuvette 335nm all aster discarded and using its a and has the absorbance B&L Spec-20 229 spectrophotometer. Standards were prepared using 25.6 g/1 (lml/100ml) Na-K-Cl solution and treated in the same manner. Boron Boron was measured using the by Lico et al. using (1982). recrystallized distilled water). carmine method outlined Stock B standard was first prepared Na2B40*10H20 (place overnight in 0.2ml of the 50% field dilution is mixed with 2ml of distilled H 20 and 2 drops of concentrated H C l , to which 10ml of concentrated H 2S04 was slowly add e d . The mixture is iced for 30 minutes to c o o l . Then 10ml of carmine solution (0.5g carmine dissolved H 2S04 ) is added, mixed and allowed to stand absorbance blanks, measured of at a in 1000ml very well for of concentrated using a vibrating mixer, 1 hour mixing occasionally. standards, wavelength of and the 600nm The samples using a B&L were Spec-20 spectrophotometer. n h 4n The procedure NH4N in analysis followed Collins (1975). an adaptation 10.0ml of the of 50% the field dilution is pipeted into a 250ml flask, brought up to 100ml with distilled minutes. H 20, The mixture and boiled a hot plate for 5 is cooled on ice and the pH adjusted to 7.00 with IN and 0. IN NaOH. formaldehyde solution mixed well, on is then 5.0ml of reagent grade pipeted into the 37 solution, and the mixture heated to 40°C on a hot plate. 230 The mixture is quickly cooled to room temperature using icewater bath, and titrated 8.6 to pH using 0.02N NaOH. A blank was carried along with each batch of samples. Chloride Chloride was measured on a using the Mohr titration method 50ul non-diluted (Brown et al., sample 1970). This method involved the addition of 50ml of distilled water to several drops of K 2Cr04 reagent, and titration the sample, with standardize prepared from silver-nitrate Na A.A.S solution. standard that was Standards were check with NaCl salt standard. Bromide Bromide was Presely (1971) For this measured using as modified by analysis, 50ul the procedure Long and Gudramovics of acidified 50% field sample was added to 950ul of distilled water. of phenol red-acetate buffer .IN NaOH brought up to outlined by (1982). diluted To this, 2 5ml (0.016g phenol red plus 2ml of 100ml mixed 1:4 with acetate buffer with distilled water, then (18.lg anhydrous Na-Acetate, 7ml glacial acetic acid brought up to 1000ml with distilled H 20 ) ) and 4ml of adjustable repipets. Chloromine-T (. 56g/l) are added using After mixing for exactly 30 seconds, 10ml of Na-thiosulfate is added (0.955g/1000ml anhydrous Nathiosulfate), mixed, and the absorbance measured using a B&L Spec-20 student grade spectrophotometer. at 592nm Trials 231 showed that HN03 did not affect the development of but the method However, the is sensitive to the presence of color, iodine. I concentration of these waters are generally less than 5% of the Br concentration, with in the estimated error of the analysis. grade K B r , and along Standards with a were blank, made were from reagent measured in an identical fashion. Iodine Iodine was measured using an adaptation of the method in Brown et overnight al. with (1970). lg of Non-acidified CaO to remove sample iron. was The treated sample is filtered and 25.0ml are added to 75ml of distilled H 20. The pH is adjusted to 6.2 with 1M H 2S04 and/or 0.1M NH40H. an iodine flask, glacial acetic mixed, and added until acid, the 6ml Approximately 15ml of and flask of 273g/l Na-acetate, 5ml of is stoppered Na-formate saturated 5ml Br2 for solution the yellow color disappears, of In 2. 2M water 5 are minutes. (50g/100ml) the is Br vapors in the flask are blown out with air, and the sides washed down with distilled H 20. Then lg of KI and 3ml of 3.6M H 2S04 are added, the solution is well stirred, tightly stoppered, allowed 5 minutes, to 1 stand to 2ml in of the dark starch for indicator minutes. is added and After and 5 the solution titrated with standardized 0.01N Na2S 20 3 until the endpoint is procedure. reached. A blank is carried through this 232 Sulfate Sulfate was outlined in used, measured A.P.I using (1968). to which 50ml the gravimetric 50ml of non-diluted sample were of distilled water were added, concentrated H C 1 , and 10ml of BaCl solution mixture hours, is is loosely covered and heated to through Watman #42 filter 30°C paper of The for several The mixture which is then dried for 1 hour at 30°C, crucible, and at minutes. The crucibles were cooled in a desiccator and re­ weighed. A blank and a series of standards were measured in a similar ashed fashion, placed 1ml (100g/l) . cooled and allowed to stand overnight. washed procedure 850°C in a pre-weighed ceramic in a muffle furnace for 10 and a calibration curve was prepared. Two calibration curves were required, one for higher concentrations. one below 25mg/l, and The results reported in this study are calculated from the calibration curve. TDS and Density TDS values components. were calculated by summing This procedure was used because measured it was found very difficult to get repeatable weights by evaporation and weighing salts hydroscopic determined directly, nature on 25°C. The before cooling 25 of most the samples brine 25°C in warmed a the result components. by weighing pyconometer was to likely in the Density was a pyconometer slightly water of bath. to at remove gas Density was 233 calculated for the remaining samples from the least squares line relating TDS to density: TDS * 7.102xl0"7 relationship, + brine 0.996 (r2 analyses = 0.9) obtained were put on the same density scale. best-fit Density = log . Using from other this sources Adjustment to formation temperature and pressure can be made using: p* = p * exp [B* (P—0.1) (kg/m3) at density at temperature 25oC and T - A* (T-25) ] where p* = density oC 1 MPa, and pressure P (MPa) , p = A = 5xl0-4 oC- 1 , B = 4.3xl0-4 MPa- 1 . Oxygen and Hydrogen Isotopes The oxygen (180/160) and hydrogen (D/H) stable isotopic ratios were Laboratory, Several measured University 18/ 16o (Princeton, at of analyses New the Waterloo, were Jersey), Environmental made and Waterloo, at Teledyne were checked replicate samples measured at Waterloo. Isotope Ontario. Laboratory, with Identical several results within, analytic error and variance, were obtained from each laboratory. Oxygen isotope analysis utilized 72 hour equilibration with C02 , and deuterium analysis used complete distillation techniques. detail Fritz in et al. All methods (1986). are discussed Measured ratios in are normalized to SMOW and have a precision of + 2°/oo for D and + 0.2°/oo for oxygen. However, repeat analysis of samples show larger ranges of measured values, lsO and 3.9°/oo for D: up to 1.2 2°/oo for 234 TABLE B-2 Variability in 180/160 and D/H SAMPLE 3081 3082 1085 1086 2092 2097 2100 8040 3042 2020 1004 10043 3007 3082 3086 -6.19,-5.86 -3.50,-4.77 -2.58,-2.16 -5.81,-5.02 -3.39 0.45 0.23,0.37 -2.90,-3.03 -2.03 0.75 -0.60,—0.80 -0.93,-1.17 -4.51 -3.50,-4.77 -5.81,-5.02 D/H -52.7 -46.5,-46.1 -43.6 -55.8 -48.2,-51.4 -38.6,-41.4 -40.8 -46.5 -40.5,-37.9 -37.4,-39.9 -31.5 -32.9,-29.0 -53.9,-50.1 -46.5,-46.1 -55.8 Deuterium values were corrected for activity following Sofer and Gat (1975) : del aD = del CD - [6.1MCa + 5.lMMg + 2.4MK + 0.4MN a ] and oxygen isotope activities were corrected to concentration using: del cl80 = del al80 - l . H M Mg + 0.47MCa Sofer and Gat (1972). - 0.16MR , from 235 Strontium Isotopes Strontium using the (87Sr/86Sr) procedures isotopic Throughout this procedure, distilled HC1 was used. lml of non-diluted column containing first Stueber loaded 100ml of Dowex resin onto et measured (1984). is by were al. sample outlined ratios a (8x-200). large The Sr was then eluted from the column using standardized 2N distilled H C 1 . A calibration curve prepared for this column showed that Sr was separated 1150ml to eluting from 1400ml a Ca and of acid. Ca-Sr eluted after passing The column was standard (having a through standardized by similar absolute concentration to typical samples), collecting the eluent in 25ml sub-samples, methods. new, and analyzed acid washed, scratch-free overnight beaker was loosely covered and on a periodically with H C l . 2N HCl, completely, making and is eluted from slightly using A.A.S its beaker, warm and hot slowly plate. The sides were washed down The residue is then taken up in 5ml certain loaded (8X-200, 50ml volume) Sr Ca-Sr The 1150-1400ml eluent volume was collected in a evaporated of for onto to dissolve the a small column of residue Dowex resin along with 10ml of distilled H 20. this standardized 2N H C l . column using 450 to 600ml The of The eluent is collected in an acid- washed, scratch free beaker, and a 5ml aliquot of the eluent is taken and analyzed for Sr and Ca. was dried slowly on a hotplate The remaining eluent overnight, periodically 236 washing down cooled, the the beaker residue aliquot containing sides with acid. is taken up 10-15ug of in 10ml Sr Once dried of 2N HCl is transferred, and and an based on the measured Sr in the eluent, into a 10ml acid washed glass beaker, the that beaker parafilm o7 Sr/ o fi is slowly evaporated on a hot plate, sides for with transport HCl. The sample to Argonne was National washing covered with Laboratory for , Sr analysis. samples with Both 50ml of columns are concentrated regenerated distilled between HCl washed through with at least 5 column volumes of distilled water. Each water column is after periodically several back-flushed samples. At the with deionized laboratory, the Sr residue is taken up in 50ul of distilled HCl and loaded onto the tungsten-rhenium filament and loaded into a VG-Isotopes Inc. MM54R instrument 90° arc mass spectrometer is calibrated to N.B.S. for analysis. standard #987 The having a 87Sr/86Sr of 0.710201 ± 0.040/mil Subsurface Temperature and Pressure Subsurface temperatures measured in the Michigan conditions were Vugranovich (1986). used 33m. in this wells temperatures A study, Geophysical sampled estimated logs were for a few basin, are very therefore, using geothermal starting and and pressures methods gradient subsurface outlined of at a temperature obtained indicated locations. These in 2 3°C/km is of at for a number approximate seldom 10°C of the bottom-hole temperatures are 237 suspect however, this data as there are no means for determining from if the geophysical probe had equilibrated before temperature was recorded (Vugranovich, personal communications). Variations in measured temperature, equilibration or real variations due either to non­ in basin gradients are illustrated by Figure B - 2 . temperature This figure shows formation temperatures that Vugranovich (1986) thought to be reliable, and are plotted versus production d e p t h . As this figure shows, measured temperatures vary considerably around the assumed geothermal gradient. Subsurface pressures hydrostatic ( Wilson Changes subsurface in in the and Long, basin 1985; pressures are are thought to Vugranovich, therefore, be 1986). dependent upon brine salinity as a function of formation depth in the basin. individual The characteristic formation brine of the basin compositions, and shape, the location of production within unique areas of the basin result in a poor correlation between salinity, brine density, and production elevation least best-fit or depth. The squares relating brine density to production elevation is: line density = 1.171 -4.264xl0-4 * (production elevation in met e r s ) . poor correlation (r2 = -0.367) of this line suggests The that predicting pressure versus depth in the basin based on brine salinity or density would not provide useful information. TEMPERATURE C 25 30 • 5 Q j T DEPTH a^ a aa 50 55 ■ ^ ® -■ - A 0A*a!NcPb*'*d?A0 ~ a “a ^ A DUNDEE RICHFIELD A A q O " ' v° 0 X ° A ^ ° 0 O AA A NIAGARA/ SALINA ORDOVICIAN o '0% 0 *o''^ * & 2000 - 2500 - Figure B - 2 . F o r m a t i o n t e m p e r a t u r e vs. p r o d u c t i o n e l e v a t i o n (meters). A l s o s h o w n is a g e o t h e r m a l g r a d i e n t of 23 C / k m , s t a r t i n g at 10° at 3 3m. Data from V u g r a n o v i c h (1986). 238 (meters) O A TRAVERSE a ■ 0^4" 1500 - 60 • '.i-Arftf A a 45 A • • ^6'a ® A 40 ■ .• >0 A ■ *«4 • A .* A 1000 35 239 ANALYTIC ERRORS-CHARGE BALANCE One method available for determining the reliability of chemical water balances. as: analyses In this is study, the calculation of charge balances were charge calculated (CATIONS-ANIONS)*100/(CATIONS+ANIONS), where CATIONS and ANIONS represent the sum of cation and anion equivalences, respectively. 5% error. Most charge balances were found to be under It should be realized that charge balances for highly saline formation waters can be misleading and do not represent salinity First, the same waters. charge associated single degree This is balance with of the For several example, the brines is C l , balanced by Ca, analytic errors represent the are sum of result calculations determining anion. reliability cations dominant and two cations, these error normally considered salinity waters, 5% for example, error in salinities a single or in error offset in large, a these Because calculations their by really associated error The combined however, and may Secondly, acceptable for charge normal can represent a very large several of these waters. the K, and Sr. account for some of the charge imbalance. balance normal phenomenon. anion offset by the concentration and error in C l . error in the cations may be quite for include Na, Mg, additive, of as components For example, at a +5% the high error in charge in a typical Michigan basin water with 350,000 mg/1 TDS, can represent 21,000mg/l S04o an error in measurement of about 240 ERROR ESTIMATE An important estimation of of analytic particularly brines part chemical precision important requiring any in large and studying dilutions analysis accuracy. highly for is an This is concentrated analysis. Error in this study results from non-determinate sources, and can be estimated or calculated using propagation of error methods. Precision of the different component analyses was determined by measuring and is ten listed by replications component of the analysis mean, in Table and compared (SD* 10 0/MEAN) concentrations. a single sample B- 3 (#2078), Generally, the as represented by 1 standard deviation analytic precision, variation of It is should less be by the coefficient than noted 5% of that the these of measured precision values do not reflect human error in the field dilution of the brines. Also listed in this table are the estimated accuracy in the analyses. The propagation of error method can be used to estimate the minimum error (maximum accuracy) employed in this study were generally (except taken for into (see below). in the analytic methods The calculated errors less than 5% of the measured concentrations S04 ). account. However, other For example, considerations it was the must be authors experience that the brines were difficult to work with both in the field and laboratory, viscosity, due to their high salinities, and presence of large amounts of species such as iron which are known to interfere with many of the analytic 241 TABLE B-3 ANALYTIC PRECISION AND SAMPLE COMPARISONS Zimmerman #19-A #2078 Niagara/Salina Mean Stnd. mg/1 Dev. * * * * * * * Ca 109160 Mg 11000 Na 27760 24100 K 3586 Sr Cl 274750 Br 3010 HC03 10 S04 22 * Rb 77.7 * Cs 14.3 Si 1.32 1160 152 135 260 24 4250 80 - Coeff. of variance 1.06 1.38 0.48 1.08 0.67 1 .60 2.66 - 0.37 0.43 0.48 3.00 - - - Charge Balance 2.91% * = average of 10 analyses, other species n=3. - = Standard deviation out of range. Coeff. of variance= Stnd. deviation *100/mean. Wm. Schmidt B-l #1024 Traverse brine This study Ca 30200 Mg 5560 Na 78100 K 928 Sr 1140 Cl 194000 Br 1280 HC03 5.4 S04 106 Cs 2.2 I 12 Li 32 Rb 3.3 Si 4.28 NH4 106 SPG 1.2263 Charge balance -0.73% SAMPLE COMPARISION Wm. Schmidt B-l M.D.N.R. (1976) 31500 7460 81500 1760 1210 182000 1260 NA NA 2.36 5 33 NA NA NA 1.225 +5.97% Sample 242 methods used. Considering this, the accuracy of the analysis were estimated (Table concentrations. For alkalinity, and B, B-l) to some error be 10% of components cannot be the measured such as predicted S04 , and is estimated to be much higher ( A.P.I, 1968) . Maximum accuracy of the analyses were computed by error propagation here. methods. Two Propagation of typical error examples for are presented procedures following X=AaBbCc ... is: Sx/X = [ (SA/A)2 + (Sg/B)2 + (SQ/ C ) 2 + ...], (a,b,c = -1,0,1) when the procedure follows X=A+B+C, the error is calculated as: S2X = S2A + s 2B + S 2C , and when the procedure follows F = Ax + By + C z , the error is calculated as: S 2 (X) = A 2S2 ( x ) SA , SB , and calculated Sq value respectively. the pipets, + B2S2 (y) + C2S2 (z). are the (X) , and variances measured For all cases, Sx , in the values unknown A, B, or and C, Table B- 4 lists the glassware tolerances for volumetric, standards, and the balance used in this work. Example 1) Error in Ca (40,000 mg/1) analysis. This this error study, and is typical includes of all error dilutions, and in the measurement. A.A.S in analysis field made dilution, in lab Field dilution consisted of making a 50% dilution by adding 125ml of sample to 125ml of acidified water (termed the dilution factor, df= 2 ) . This results in the following error: Sx = [ 0.082 + 0.032 + 0.082 + 0.032 ]1/ 2 = 0.12ml, where glassware tolerances from Table B-2 are used as the variance. A 1:1000 dilution of the 243 TABLE B-4 GLASSWARE TOLERANCES Class A pipets Volume Accuracy ml ml 1 0.006 5 0.01 10 0.02 20 0.03 25 0.03 50 0.05 100 0.08 Volumetries Volume Tolerance ml ml 50 0.05 100 0.08 200 0.10 250 0.12 500 0.20 1000 0.30 Eppendorf pipets Volume Accuracy Precision ul ul ul 10 50 100 200 250 500 1000 0.06 0.30 0.60 1.20 1.50 3.00 6.00 0.04 0.10 0.20 0.40 0.50 1.00 2.00 244 field dilution is next prepared in the lab, (1ml of field dilution brought up to 1000ml). The error in this mixture is calculated as: [Q.0022 + 0.302 ]1/ 2 = 0.30ml, bringing the total error at this point to [0.122ml + 0. 302m l ] 1//2=0. 32ml. 10ml of the sample (and LaCl2 before analysis, ml. The final standards) were with an error to sample volume error added .022 + is 1ml to .0022 = calculated to of .02 be 0.32ml. The next error to consider is in the concentration of the standards. 1000mg/l+10%. Stock standards have a concentration of Preparing 100ml of 20mg/l standard results in an error of Sx = 10* [(10/ 1000)2 + (0.006/1)2 + (0.006/1)2 + (0.08/100)2 ]1/ 2 ~ 0.014 = 0.14 m g / 1 . estimated by repeated measurements Instrument error was of standards, and was found to be approximately 5% of the measured concentration, or in this example 0.5mg/l. The resulting error measuring a 20mg/l concentration is calculated to be in [0.152 + 0.52 ]1/ 2 = 0.52mg/l. With these calculated errors, the error in measuring a brine having 40,000 mg/1 of Ca is: N 1 = N 2V 2*df / V x= 20*1000*2/1 = 40,000mg/l Sni/Nj. - [* Si 255 ID Br Cl ALK I as h c o 3 so4 B n 18o nd ° /0 0 °/oo BEREA 7001 940 7005 1600 7006 1840 200000 176000 209000 25 28 100 25 25 85 10 17 11 TRAVERSE 1101 710 1102 2290 1103 590 1104 650 1105 880 1107 1260 1109 1420 1110 2340 1111 910 1112 1480 1113 1550 1114 1040 1115 1330 1116 730 1117 1000 1118 990 1119 710 1008 1560 1009 1510 1011 1930 1014 1510 1017 880 1028 890 1024 1260 1048 1247 1049 1050 1085 900 1088 720 162000 156000 177000 160000 176000 182000 194000 194000 171000 187000 187000 168000 182000 158000 158000 165000 165000 158000 155000 188000 196000 140000 175000 182000 184600 182000 175000 136000 13 4 22 2 24 110 16 4 31 32 6 215 1 9 17 5 85 2 7 10 100 2 28 30 73 5 2 20 12 160 27 18 60 68 7 73 1 11 80 24 6 9 44 10 70 7 5 5 4 155 33 38 18 208 22 36 20 297 24 31 25 86 68 -0.57 -23.80 11 18 59 27 -0.70 -31.50 59 12 109 18 -3.60 -40.00 3 12 67 -0.49 -32.50 5 12 106 0.56 -29.10 18 10 162 117 18 12 150 61 71 28 -1.83 -43.60 156 10 607 -7.06 -61.20 DUNDEE 3016 1920 3301 860 3302 1250 3304 1190 3305 1220 3306 315 3307 820 3309 1460 3311 2390 3312 1320 3313 980 3314 ' 680 3315 590 3002 1180 3003 1070 202000 59 162000 63 178000 59 160000 43 180000 63 154000 2 131000 52 191000 39 212000 139 175000 49 120000 71 152000 54 164000 9 186000 26 155000 23 20 6 5 10 12 5 4 12 26 11 8 3 7 15 18 1.10 -10.70 0.29 -24.10 103 84 1.31 -35.50 317 150 410 122 810 676 140 40 33 1130 364 660 141 39 0.20 -30.80 295 11 -2.38 -28.10 87Sr 0.70915 0.70909 NH,N NaD °/oo MCI, jneq/I 50 1.04 3240.4 64 -14.80 2580.6 126 3148.7 193 180 121 146 83 0.70940 76 0.70909 106 -12.43 -21.52 -34.16 -26.45 -21.21 0.70845 174 -36.89 76 -57.26 1729.9 1630.0 1349.4 1546.2 1615.0 2211.6 2942.9 4242.5 1773.5 2933.8 2819.6 2010.3 2666.9 1492.5 1987 .1 2054.1 1672.2 2627.3 2563.1 3206.7 2654.7 1446.4 1432 .1 1988.4 2207.7 2314.3 1657.1 891. 5 0.70813 216 -23.69 3188.6 1633.8 2352.6 2084.5 2197.3 573.0 1683.3 2482.8 4641.! 2314. 1744.1 1383.7 1269.0 119 -23.84 1680.9 29 -21.50 1704.5 256 ID Br ALK as h c o 3 DUNDEE (continued) 3004 690 164000 20 3007 750 169000 64 3012 1420 185000 28 3015 1860 202000 51 3022 1020 174000 37 3029 1240 185000 43 3033 1570 191000 27 3042 1140 181000 11 *3043 1090 185000 35 3051 1500 169000 10 3052 480 162000 17 3070 1220 189000 2 3071 1290 198000 29 3027 1190 186000 28 3034 1570 188000 27 3025 780 172000 75 3023 950 149000 21 3047 1090 168000 40 3039 1190 188000 42 3026 790 192000 86 3063 650 158000 27 3070 1220 189000 2 3087 490 181000 11 3082 690 161000 84 3086 760 144000 98 3081 620 131000 106 RICHFIELD 4010 1930 4017\ 1920 4018 1870 4035 1240 4036 1050 4037 2610 4068 1200 4069 1200 4046 3200 4050 2700 440'1 2690 4406 4210 4407 4050 Cl 200000 56 203000 48 202200 45 200000 114 75800 229 182000 213 240000 240 242000 240 220000 244 191000 240 186000 278 235000 385 225000 207 I so4 B n 18o °/oo 13 28 13 19 8 19 17 13 14 20 21 15 15 10 20 10 9 9 17 12 8 10 5 7 8 12 382 319 112 109 166 139 160 137 94 200 314 31 30 220 96 295 189 67 118 429 20 31 491 364 510 745 1 20 52 80 2 19 31 8 8 38 29 112 17 74 11 109 40 33 8 348 25 161 28 0 30 0 13 0 10 0 19 0 4 66 68 34 75 81 65 371 137 180 39 82 377 137 ND °/oo -3.02 -28.60 -4.51 -52.00 -0.40 -34.20 0.43 -0.53 -2.03 -1.05 -26.10 -30.80 -39.20 -30.95 -6.11 -47.60 31 66 37 85 26 6 53 47 28 1 31 11 DETROIT RIVER 5019 3060 179000 326 57 2 383 5030 3750 251000 100 25 54 134 87Sr n h 4n NaD °/oo 64 -23.65 -46.04 228 -25.69 200 45 162 -18.58 185 -21.66 0.70831 107 -31.95 174 -22.56 0.70838 -43.81 -3.39 -41.60 125 164 71 -50.26 0.70898 81 -33.91 161 135 -22.06 73 -36.16 -4.02 -46.30 -5.71 -55.80 -6.58 -52.70 109 73 -40.45 115 -50.45 78 -48.57 -4.99 -55.40 -2.27 -39.90 -0.38 -30.00 1.49 -27.00 4.31 -51.70 2.93 -41.60 2.58 -51.70 4.36 -16.70 mc12 meq/I 1066.0 1326.4 2206.7 3162.1 1641.8 1889.6 2320.3 1729.7 2185.7 1422.9 795.8 1947.6 1766.1 1663.5 2861.8 1089.7 1524.8 1898.6 2036.0 1414.7 1249.2 1947.6 661.4 1387.0 1309.1 925.5 214 3272.9 0.70819 203 -15.24 3193.9 198 3138.9 0.70809 401 -37.99 3839.4 115 1682.9 242 3939.4 4979.7 -22.96 5269.7 333 4818.7 4337.3 4550.2 6011.5 5706.0 441 -36.13 4524.6 0.70782 689 6.97 6503.5 Br Cl ALK as h c o 3 NIAGARA/SALINA 2206 3020 263000 614 2207 3070 248000 258 2208 1150 140000 103: 2209 690 117000 52 2210 2220 170000 31 2211 2230 168000 3 2212 2430 202000 108 2213 2640 211000 49 2214 2060 168000 32 2215 3220 236000 53 2020 3340 209000 50 2072 2730 233000 150 2077 1270 153000 150 2078 3010 265000 150 2083 1800 169000 150 2084 2360 213000 150 2089 3060 244000 150 2090 2940 253000 374 2091 1820 190000 207 2092 2500 218000 17 2093 3300 248000 36 2100 3110 239000 39 2101 2980 239000 240 2097 2700 223000 123 2096 2700 211000 84 2099 3110 227000 88 2098 2560 230000 352 (ft Oc Ef ID H 257 28 10 6 27 22 : 152 7 71 19 70 23 30 22 29 13 87 14 154 22 18 19 110 9 56 32 119 50 22 41 106 64 131 50 75 31 85 29 28 17 34 19 25 22 42 21 52 27 75 38 82 54 75 28 34 TRENTON-BLACK RIVER 6601 1130 142000 27 6602 1430 163000 39 6603 1020 122000 40 6604 980 121000 43 6605 870 116000 55 6606 760 104000 90 6073 750 91000 25 6074 1080 130000 25 6075 1080 127000 25 6076 1040 127000 25 6095 1250 143000 67 6094 1160 140000 39 9 11 8 8 7 6 10 13 13 10 15 26 St. PETER 8040 3100 20 250000 10 369 113 393 530 249 717 250 238 125 125 100 100 B n 18o nd °/oo °/oo 220 0.75 -37.40 81 106 239 2.87 -48.70 354 346 498 226 152 25 -3.39 -49.80 123 98 0.30 -40.80 72 81 -1.99 -24.30 72 61 86 87Sr NHaN 0.70799 437 235 283 0.70879 56 672 784 1087 1053 667 0.70830 356 415 549 476 451 431 641 588 NaD °/oo -22.15 -24.61 -32.86 -19.84 -7.32 MCI, meq/I 7383.4 6220.2. 3185.5 2286.4 3460.4 3202.1 4138.8 4526.9 3342.9 5503.8 4148.3 4989.1 3534.2 6437.0 3728.1 5014.3 5977 .9 6426.4 4155.6 4879.7 5969.7 6020.5 5972 .5 4747.5 4593.4 4764.0 5400.7 6 13 -1.85 -26.40 13 15 15 -1.76 -26.70 21 -1.99 -24.30 1795.2 2542.8 1662.1 1593.7 1409.0 1261.1 45 1059.1 73 -20.39 1567 .0 70 1557.6 78 1531.2 120 -20.15 1696.6 0.71031 126 -17.97 1635.7 0 107 -2.96 -46.50 0.70920 247 -26.66 5367.3 BIBLIOGRAPHY 258 BIBLIOGRAPHY Ahrens L.H. 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